Question: Extract the answer to the question from the following context. Question: What nation state is PortMiami in? Context: Miami is home to one of the largest ports in the United States, the PortMiami. It is the largest cruise ship port in the world. The port is often called the "Cruise Capital of the World" and the "Cargo Gateway of the Americas". It has retained its status as the number one cruise/passenger port in the world for well over a decade accommodating the largest cruise ships and the major cruise lines. In 2007, the port served 3,787,410 passengers. Additionally, the port is one of the nation's busiest cargo ports, importing 7.8 million tons of cargo in 2007. Among North American ports, it ranks second only to the Port of South Louisiana in New Orleans in terms of cargo tonnage imported/exported from Latin America. The port is on 518 acres (2 km2) and has 7 passenger terminals. China is the port's number one import country, and Honduras is the number one export country. Miami has the world's largest amount of cruise line headquarters, home to: Carnival Cruise Lines, Celebrity Cruises, Norwegian Cruise Line, Oceania Cruises, and Royal Caribbean International. In 2014, the Port of Miami Tunnel was completed and will serve the PortMiami.
Answer: the United States

Question: Extract the answer to the question from the following context. Question: Who determines if a change in pitch exists? Context: The just-noticeable difference (jnd) (the threshold at which a change is perceived) depends on the tone's frequency content. Below 500 Hz, the jnd is about 3 Hz for sine waves, and 1 Hz for complex tones; above 1000 Hz, the jnd for sine waves is about 0.6% (about 10 cents). The jnd is typically tested by playing two tones in quick succession with the listener asked if there was a difference in their pitches. The jnd becomes smaller if the two tones are played simultaneously as the listener is then able to discern beat frequencies. The total number of perceptible pitch steps in the range of human hearing is about 1,400; the total number of notes in the equal-tempered scale, from 16 to 16,000 Hz, is 120.
Answer: the listener

Question: Extract the answer to the question from the following context. Question: How many stations make up the rail network? Context: New York City's commuter rail network is the largest in North America. The rail network, connecting New York City to its suburbs, consists of the Long Island Rail Road, Metro-North Railroad, and New Jersey Transit. The combined systems converge at Grand Central Terminal and Pennsylvania Station and contain more than 250 stations and 20 rail lines. In Queens, the elevated AirTrain people mover system connects JFK International Airport to the New York City Subway and the Long Island Rail Road; a separate AirTrain system is planned alongside the Grand Central Parkway to connect LaGuardia Airport to these transit systems. For intercity rail, New York City is served by Amtrak, whose busiest station by a significant margin is Pennsylvania Station on the West Side of Manhattan, from which Amtrak provides connections to Boston, Philadelphia, and Washington, D.C. along the Northeast Corridor, as well as long-distance train service to other North American cities.
Answer:
more than 250 stations