Definition: In this task you will be given a passage and a yes/no question based on the passage. You should answer the question using the information from the passage.
Input: passage: Mammoth Cave National Park is a U.S. national park in central Kentucky, encompassing portions of Mammoth Cave, the longest cave system known in the world. Since the 1972 unification of Mammoth Cave with the even-longer system under Flint Ridge to the north, the official name of the system has been the Mammoth--Flint Ridge Cave System. The park was established as a national park on July 1, 1941. It became a World Heritage Site on October 27, 1981, and an international Biosphere Reserve on September 26, 1990.
 question: is mammoth cave the longest cave in the world?

Yes