Question: What has a station on 23rd Street and Sixth Avenue in Chelsea and is operated by the Port Authority of New York and New Jersey?

Context paragraphs:
28th Street (IRT Sixth Avenue Line): 28th Street was a station on the demolished IRT Sixth Avenue Line.  It had two tracks and two side platforms.  It was served by trains from the IRT Sixth Avenue Line.  From 1910 to 1937 it also had a connection to the 28th Street (H&M station).  It closed on December 4, 1938.  The next southbound stop was 23rd Street.  The next northbound stop was 33rd Street.

Eighth Avenue (IRT Sixth Avenue Line): Eighth Avenue was a station on the demolished IRT Sixth Avenue Line.  It was built in 1881 by the Manhattan Railway Company as part of an effort to connect the northern end of the Sixth Avenue Line to the Ninth Avenue Line.  It had three tracks and two side platforms, and was served by trains from the IRT Sixth Avenue Line.  As a result, it became the last station on the Sixth Avenue Line before merging at a sharp curve with the Ninth Avenue Line.  On September 11, 1905, 12 people were killed and 42 injured when a train jumped over the rails at the curve on 53rd Street between the Ninth Avenue 50th Street and 59th Street stations.  In 1932, the Independent Subway System built the 50th Street Station three blocks to the south on the Eighth Avenue Subway with an additional lower level in 1933, thus rendering the elevated station and line obsolete.  It closed on December 4, 1938.  The next southbound stop was 50th Street.  The next northbound stop was 59th Street.

23rd Street (IND Sixth Avenue Line): 23rd Street is a local station on the IND Sixth Avenue Line of the New York City Subway.  Located at the intersection of 23rd Street and Sixth Avenue in Manhattan, it is served by the F train at all times, and by the M train on weekdays.  This station and 14th Street are the only two local stations on the Sixth Avenue Line.

23rd Street station (PATH): 23rd Street is a station on the PATH system.  Located at the intersection of 23rd Street and Sixth Avenue in the Chelsea neighborhood of Manhattan, New York City, it is served by the Hoboken–33rd Street and Journal Square–33rd Street lines on weekdays, and by the Journal Square–33rd Street (via Hoboken) line on weekends.

Port Authority Bus Terminal: The Port Authority Bus Terminal (PABT) is the main gateway for interstate buses into Manhattan in New York City.  It is owned and operated by the Port Authority of New York and New Jersey (PANYNJ).  Colloquially called the Port Authority, the bus terminal is located in Midtown at 625 Eighth Avenue between 40th Street and 42nd Street, one block east of the Lincoln Tunnel and one block west of Times Square.  The PABT, opened in 1950 between 8th and 9th Avenues and 40th and 41st Streets, was built to consolidate the many different private terminals spread across Midtown Manhattan.  A second wing extending to 42nd Street was added in 1979.  It is one of three bus terminals operated by the PANYNJ, the others being the George Washington Bridge Bus Station in Upper Manhattan and the Journal Square Transportation Center in Jersey City.

Seventh Avenue (IND Queens Boulevard Line): Seventh Avenue is a station on the IND Sixth Avenue Line and the IND Queens Boulevard Line of the New York City Subway.  Located at the intersection of Seventh Avenue and 53rd Street in Manhattan, it is served by the D and E trains at all times, and the B train weekdays.  The station is announced as Seventh Avenue–53rd Street, in the style of other stations that orient east-west along 53rd Street (such as Fifth Avenue/53rd Street and Lexington Avenue–53rd Street), as well as to prevent confusion with Seventh Avenue along Flatbush Avenue in Brooklyn, which is also served by the B.

PATH (rail system): Port Authority Trans-Hudson, abbreviated PATH, is a rapid transit system serving Newark, Harrison, Hoboken, and Jersey City in metropolitan northern New Jersey, as well as lower and midtown Manhattan in New York City.  The PATH is operated by, and named after, the Port Authority of New York and New Jersey.  PATH trains run 24 hours a day and 7 days a week.

23rd Street (IRT Sixth Avenue Line): 23rd Street was a station on the demolished IRT Sixth Avenue Line.  It had two tracks and two side platforms.  It was served by trains from the IRT Sixth Avenue Line.  It closed on December 4, 1938.  The next southbound stop was 18th Street.  The next northbound stop was 28th Street.  Two years later the rapid transit needs of the intersection were replaced by the underground 23rd Street (IND Sixth Avenue Line) subway station.

Construction of the World Trade Center: The construction of New York City's first World Trade Center complex was conceived as an urban renewal project, spearheaded by David Rockefeller, to help revitalize Lower Manhattan.  The project was developed by the Port Authority of New York and New Jersey, which hired architect Minoru Yamasaki who came up with the specific idea for twin towers.  After extensive negotiations, the New Jersey and New York state governments, which oversee the Port Authority, agreed to support the World Trade Center project, which was built at the site of Radio Row in the Lower West Side of Manhattan, New York City.  To make the agreement acceptable to New Jersey, the Port Authority agreed to take over the bankrupt Hudson & Manhattan Railroad, which brought commuters from New Jersey to the Lower Manhattan site and, upon the Port Authority's takeover of the railroad, was renamed PATH.

18th Street (IRT Sixth Avenue Line): 18th Street was a station on the demolished IRT Sixth Avenue Line.  It had two tracks and two side platforms.  It was served by trains from the IRT Sixth Avenue Line.  It closed on December 4, 1938, and was not replaced with a subway station on the IND Sixth Avenue Line.  However, one block north of the station there was a 19th Street (H&M station) that operated between 1908 and 1954.  The next southbound stop was 14th Street.  The next northbound stop was 23rd Street.

Supporting paragraphs: 23rd Street station (PATH) PATH (rail system)
Answer: PATH