Question: Back Bay, Boston is one of how many distinct neighborhoods?

Context paragraphs:
1990 Back Bay, Massachusetts train collision: The 1990 Back Bay, Massachusetts train collision was a collision between an Amtrak passenger train, the "Night Owl", and a Massachusetts Bay Transportation Authority (MBTA) Stoughton Line commuter train just outside Back Bay station in Boston, Massachusetts.  An investigation by the National Transportation Safety Board (NTSB) found that the Amtrak train entered a speed-restricted curve at excessive speed, causing the train to derail and crash into the MBTA commuter train on an adjoining track.  Although no one was killed in the accident, 453 people were injured and Back Bay station was closed for six days.  Total damage was estimated at $14 million.  The accident led to new speed restrictions and safety improvements in the vicinity of Back Bay and a revamp of Amtrak's locomotive engineer training program.

Neighborhoods in Plymouth, Massachusetts: There are several neighborhoods in Plymouth, Massachusetts.  With a total area of 134.0 mi² (347.0 km²), Plymouth is the largest municipality in Massachusetts by area.  In addition, with a population of 51,701 at the 2000 census and an estimated population of 57,901 in 2007, Plymouth is the second-largest town in the state by population (after Framingham.  As such, Plymouth is home to many distinct neighborhoods and geographical locations.

Neighborhoods in Boston: Boston's diverse neighborhoods serve as a political and cultural organizing mechanism.  The City of Boston's Office of Neighborhood Services has designated 23 Neighborhoods in the city:

Back Bay station: Back Bay is an intercity rail, commuter rail, and rapid transit train station located just south of Copley Square in the Back Bay and South End neighborhoods of Boston, Massachusetts.  The present building, designed by Kallmann McKinnell & Wood, opened in 1987.  It replaced the New Haven Railroad's older Back Bay station - which opened in 1928 as a replacement for an 1899-built station - as well as the New York Central's Huntington Avenue and Trinity Place stations which had been demolished in 1964.

Back Bay, Boston: Back Bay is an officially recognized neighborhood of Boston, Massachusetts.  It is most famous for its rows of Victorian brownstone homes — considered one of the best preserved examples of 19th-century urban design in the United States — as well as numerous architecturally significant individual buildings, and cultural institutions such as the Boston Public Library.  It is also a fashionable shopping destination (especially Newbury and Boylston Streets, and the adjacent Prudential Center and Copley Place malls) and home to some of Boston's tallest office buildings, the Hynes Convention Center, and numerous major hotels.

Neighborhoods of New Haven, Connecticut: The city of New Haven, Connecticut has many distinct neighborhoods.  In addition to Downtown, centered on the central business district and the Green, are the following neighborhoods: the west central neighborhoods of Dixwell and Dwight; the southern neighborhoods of The Hill, historic water-front City Point (or Oyster Point), and the harborside district of Long Wharf; the western neighborhoods of Edgewood, West River, Westville, Amity, and West Rock; East Rock, Cedar Hill, Prospect Hill, and Newhallville in the northern side of town; the east central neighborhoods of Mill River and Wooster Square, an Italian-American neighborhood; Fair Haven, an immigrant community located between the Mill and Quinnipiac rivers; Quinnipiac Meadows and Fair Haven Heights across the Quinnipiac River; and facing the eastern side of the harbor, The Annex and East Shore (or Morris Cove).

List of Salt Lake City neighborhoods: This is a list of neighborhoods in Salt Lake City.  As a major city, Salt Lake City urbanized in the early 1900s and now has many distinct neighborhoods.

List of neighborhoods in Fort Lauderdale, Florida: Fort Lauderdale, Florida, unlike many cities, has an official program for recognizing official neighborhoods.  Under the Neighborhood Organization Recognition Program , over 60 distinct neighborhoods have received official recognition from the city.  An additional 25-30 neighborhoods exist without official recognition, although the city's neighborhood map displays them as well.

101 Clarendon Street: 101 Clarendon Street, also known as Columbus Center, was a proposed skyscraper planned for Boston, Massachusetts.  If completed, it would have stood as the 25th-tallest building in Boston.  Continuing on the trend established by the Prudential Tower in 1964, the completed building would have concealed more of the Massachusetts Turnpike (I-90) by utilizing air rights above it.  The location would have been above the turnpike, directly to the east of Back Bay station and south of Copley Square in the Back Bay neighborhood of Boston.  The project would have "united the city’s Back Bay and South End neighborhoods."

Southwest Corridor Park: Southwest Corridor Park is a linear urban park in Boston, Massachusetts, part of the Metropolitan Park System of Greater Boston and managed by the Massachusetts Department of Conservation and Recreation (DCR).  It extends from the South End and Back Bay neighborhoods south for almost five miles (8 km), ending in the Forest Hills section of Jamaica Plain in what was originally planned to be the alignment for Interstate 95 to Boston.  It closely follows the routes of regional Amtrak and Commuter Rail lines and the Massachusetts Bay Transportation Authority (MBTA) Orange Line rapid transit rail line, from its Back Bay Station to its terminus at Forest Hills station.  It features tennis courts, basketball courts, playgrounds, and walking, jogging, and biking paths.

Supporting paragraphs: Back Bay, Boston Neighborhoods in Boston
Answer: 23