Given the question: Information: - A combined statistical area (CSA) is composed of adjacent metropolitan (MSA) and micropolitan statistical areas (SA) in the United States and Puerto Rico that can demonstrate economic or social linkage. The United States Office of Management and Budget defines a CSA as consisting of various combinations of adjacent metropolitan and micropolitan areas with economic ties measured by commuting patterns. These areas that combine retain their own designations as metropolitan or micropolitan statistical areas within the larger combined statistical area. - Bay Area Rapid Transit (BART) is a public transportation system serving the San Francisco Bay Area. The rapid transit elevated and subway system connects San Francisco with cities in Alameda, Contra Costa, and San Mateo counties. BART operates 5 routes on of track connecting 44 stations, plus a automated guideway transit line to the Oakland International Airport which adds a 45th station. A spur line in eastern Contra Costa County will utilize other rail technologies. With an average of 420,000 weekday passengers and 126 million annual passengers in fiscal year 2015, BART is the fifth-busiest heavy rail rapid transit system in the United States. Growth in ridership slowed rapidly in 2016, reflecting a national trend of declining use of public transit. The name is spoken "Bart", never "B-A-R-T." - The Twin Peaks Tunnel is a -long light rail/streetcar tunnel in San Francisco, California. The tunnel runs under the Twin Peaks and is used by the K Ingleside, L Taraval, M Ocean View, and T Third Street Muni Metro lines. The S Castro Shuttle also uses the tunnel for AT&T Park game day runs. History and background. The tunnel was opened on February 3, 1918. The eastern entrance to the tunnel is located near the intersection of Market and Castro streets in the Castro neighborhood, and the western entrance is located at West Portal Avenue and Ulloa Street in the West Portal neighborhood. - Light rail, light rail transit (LRT) or fast tram is urban public transport using rolling stock similar to a tramway, but operating at a higher capacity, and often on an exclusive right-of-way. - The San Francisco Bay is a shallow estuary that drains water from approximately 40% of California. Water from the Sacramento and San Joaquin rivers, and from the Sierra Nevada mountains, passes through the bay to the Pacific Ocean. Specifically, both rivers flow into Suisun Bay, which flows through the Carquinez Strait to meet with the Napa River at the entrance to San Pablo Bay, which connects at its south end to San Francisco Bay. However, the entire group of interconnected bays is often called the "San Francisco Bay". - Muni Metro is a light rail/streetcar hybrid system serving San Francisco, California, operated by the San Francisco Municipal Railway (Muni), a division of the San Francisco Municipal Transportation Agency (SFMTA). With an average weekday ridership of 128,500 passengers as of the fourth quarter of 2014, Muni Metro is the United States' third busiest light rail system. Muni Metro operates a fleet of 151 light rail vehicles (LRV) made by Breda. - An infill station (sometimes in-fill station) is a train station built on an existing passenger rail, rapid transit, or light rail line to address demand in a location between existing stations. Such stations take advantage of existing train service and encourage new riders by providing a more convenient location. Many older transit systems have widely spaced stations and can benefit from infill stations. In some cases, new infill station are built at sites where a station had once existed many years ago, for example the CermakMcCormick Place station on the Chicago Green Line. - San Diego (Spanish for "Saint Didacus") is a major city in California, United States. It is in San Diego County, on the coast of the Pacific Ocean in Southern California, approximately south of Los Angeles and immediately adjacent to the border with Mexico. - A tunnel is an underground passageway, dug through the surrounding soil/earth/rock and enclosed except for entrance and exit, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube construction techniques rather than traditional tunnel boring methods. - California is the most populous state in the United States and the third most extensive by area. Located on the western (Pacific Ocean) coast of the U.S., California is bordered by the other U.S. states of Oregon, Nevada, and Arizona and shares an international border with the Mexican state of Baja California. The state capital is Sacramento. Los Angeles is California's most populous city, and the country's second largest after New York City. The state also has the nation's most populous county, Los Angeles County, and its largest county by area, San Bernardino County. - In United States local government, a consolidated city-county is a city and county that have been merged into one unified jurisdiction. As such it is simultaneously a city, which is a municipal corporation, and a county, which is an administrative division of a state. It has the powers and responsibilities of both types of entities. - Mission Street is a north-south arterial thoroughfare in Daly City and San Francisco, California that runs from Daly City's southern border to San Francisco's northeast waterfront. The street and San Francisco's Mission District through which it runs were named for the Spanish Mission Dolores, several blocks away from the modern route. Only the southern half is historically part of El Camino Real, which connected the missions. Part of Mission Street in Daly City is signed as part of State Route 82 (SR 82). - Castro Street Station is a Muni Metro station at the intersection of Market Street, Castro Street, and 17th Street in The Castro district of San Francisco, California. The station consists of two side platforms next to the tracks on the second level down with the concourse mezzanine level overlooking it. Uniquely among Muni Metro stations, the platforms are slightly curved due to the transition from the Market Street Subway to the Twin Peaks Tunnel between this station and the now disused Eureka Station, just southwest. - The San Francisco Bay Area (referred to locally as the Bay Area) is a populous region surrounding the San Francisco and San Pablo estuaries in Northern California. The region encompasses the major cities and metropolitan areas of San Jose, San Francisco, and Oakland, along with smaller urban and rural areas. The Bay Area's nine counties are Alameda, Contra Costa, Marin, Napa, San Francisco, San Mateo, Santa Clara, Solano, and Sonoma. Home to approximately 7.65 million people, the nine-county Bay Area contains many cities, towns, airports, and associated regional, state, and national parks, connected by a network of roads, highways, railroads, bridges, tunnels and commuter rail. The combined statistical area of the region is the second-largest in California (after the Greater Los Angeles area), the fifth-largest in the United States, and the 43rd-largest urban area in the world. - Northern California, often abbreviated NorCal, is the northern portion of the U.S. state of California. Spanning the state's northernmost 48 counties, in contrast to the 10 counties of Southern California, its main population centers include the San Francisco Bay Area (anchored by the cities of San Francisco, San Jose, and Oakland), the Greater Sacramento area (anchored by the state capital Sacramento), and the Metropolitan Fresno area (anchored by the city of Fresno). Northern California also contains redwood forests, along with the Sierra Nevada including Yosemite Valley and part of Lake Tahoe, Mount Shasta (the second-highest peak in the Cascade Range after Mount Rainier in Washington), and the northern portion of the Central Valley, one of the world's most productive agricultural regions. - The City of New York, often called New York City or simply New York, is the most populous city in the United States. With an estimated 2015 population of 8,550,405 distributed over a land area of just , New York City is also the most densely populated major city in the United States. Located at the southern tip of the state of New York, the city is the center of the New York metropolitan area, one of the most populous urban agglomerations in the world. A global power city, New York City exerts a significant impact upon commerce, finance, media, art, fashion, research, technology, education, and entertainment, its fast pace defining the term "New York minute". Home to the headquarters of the United Nations, New York is an important center for international diplomacy and has been described as the cultural and financial capital of the world. - Chicago (or ), officially the City of Chicago, is the third-most populous city in the United States, and the fifth-most populous city in North America. With over 2.7million residents, it is the most populous city in the state of Illinois and the Midwestern United States, and the county seat of Cook County. The Chicago metropolitan area, often referred to as Chicagoland, has nearly 10million people and is the third-largest in the U.S. - San Francisco (SF) (Spanish for Saint Francis) officially the City and County of San Francisco, is the cultural, commercial, and financial center of Northern California. It is the birthplace of the United Nations. Located at the north end of the San Francisco Peninsula, San Francisco is about in area, making it the smallest countyand the only consolidated city-countywithin the state of California. With a density of about 18,451 people per square mile (7,124 people per km), San Francisco is the most densely settled large city (population greater than 200,000) in California and the second-most densely populated major city in the United States after New York City. San Francisco is the fourth-most populous city in California, after Los Angeles, San Diego, and San Jose, and the 13th-most populous city in the United Stateswith a census-estimated 2015 population of 864,816. The city and its surrounding areas are known as the San Francisco Bay Area, and are a part of the larger OMB-designated San Jose-San Francisco-Oakland combined statistical area, the fifth most populous in the nation with an estimated population of 8.7 million. - The San Francisco Peninsula is a peninsula in the San Francisco Bay Area that separates San Francisco Bay from the Pacific Ocean. On its northern tip is the City and County of San Francisco. Its southern base is in northern Santa Clara County, including the cities of Palo Alto, Mountain View and Los Altos. Most of the Peninsula is occupied by San Mateo County, between San Francisco and Santa Clara counties, and including the cities and towns of Atherton, Belmont, Brisbane, Burlingame, Colma, Daly City, East Palo Alto, El Granada, Foster City, Hillsborough, Half Moon Bay, La Honda, Menlo Park, Millbrae, Pacifica, Portola Valley, Redwood City, San Bruno, San Carlos, San Mateo, South San Francisco, and Woodside. - The San Francisco Municipal Railway (SF Muni or Muni) is the public transit system for the city and county of San Francisco, California. In 2006, it served with an operating budget of about $700 million. In ridership Muni is the seventh largest transit system in the United States, with 210,848,310 rides in 2006 and the second largest in California behind Metro in Los Angeles. With a fleet average speed of , it is the slowest major urban transit system in America and one of the most expensive to operate, costing $19.21 per mile per bus and $24.37 per mile per train. However, it has more boardings per mile and more vehicles in operation than similar transit agencies. - Rapid transit, also known as heavy rail, metro, subway, tube, or underground, is a type of high-capacity public transport generally found in urban areas. Unlike buses or trams, rapid transit systems are electric railways that operate on an exclusive right-of-way, which cannot be accessed by pedestrians or other vehicles of any sort, and which is often grade separated in tunnels or on elevated railways. - The United Nations (UN) is an intergovernmental organization to promote international co-operation. A replacement for the ineffective League of Nations, the organization was established on 24 October 1945 after World War II in order to prevent another such conflict. At its founding, the UN had 51 member states; there are now 193. The headquarters of the United Nations is in Manhattan, New York City, and experiences extraterritoriality. Further main offices are situated in Geneva, Nairobi, and Vienna. The organization is financed by assessed and voluntary contributions from its member states. Its objectives include maintaining international peace and security, promoting human rights, fostering social and economic development, protecting the environment, and providing humanitarian aid in cases of famine, natural disaster, and armed conflict. - The Market Street Subway is a double-decker subway tunnel that carries Muni Metro and BART train traffic in San Francisco, California. It runs under the length of Market Street between Embarcadero Station and Castro Street Station. The upper level is used by Muni Metro lines and the lower level is used by BART lines. BART does not run through the whole subway; it turns south and runs under Mission Street southwest of Civic Center Station. The northeastern end of the BART level is connected to the Transbay Tube. On the Muni Metro level, the southwestern end of the Market Street Subway connects to the much-older Twin Peaks Tunnel, and the northeastern end connects to surface tracks along the Embarcadero. - The Transbay Tube is an underwater rail tunnel which carries Bay Area Rapid Transit's four transbay lines under San Francisco Bay between the cities of San Francisco and Oakland in California. The tube is long; including the approaches from the nearest stations (one of which is underground), it totals in length. It has a maximum depth of below sea level. - Embarcadero is a BART and Muni Metro station in the Financial District of San Francisco . The easternmost stop on the Market Street Subway , Embarcadero acts as a major hub for passenger movement throughout the San Francisco Bay Area . With 45,460 exits each weekday in 2015 , Embarcadero is the busiest station in the BART system , a title for which it vies with its western neighbor , Montgomery Street . It is the first stop in San Francisco for BART trains after crossing through the Transbay Tube from West Oakland . This station was an infill station , opening in May 1976 , three years after the rest of this section of BART 's system ; it was the first infill station in the BART system . - Los Angeles (Spanish for "The Angels"), officially the City of Los Angeles and often known by its initials L.A., is the second-most populous city in the United States (after New York City), the most populous city in California and the county seat of Los Angeles County. Situated in Southern California, Los Angeles is known for its mediterranean climate, ethnic diversity, sprawling metropolis, and as a major center of the American entertainment industry. Los Angeles lies in a large coastal basin surrounded on three sides by mountains reaching up to and over . Given the paragraphs above, decide what entity has the relation 'part of' with 'bay area rapid transit'.
The answer is:
embarcadero station