55. Every U.S. crude oil tankship with a keel laying date on or after 1/1/75, shall be equipped with an inert gas system if the tonnage is more than __________.

A. 100,000 DWT (long tons)
B. 100,000 DWT (metric tons)
C. 50,000 DWT (long tons)
D. 50,000 DWT (metric tons)