The most important thing about cotton in history is __part that is played in__Industrial Revoluton.

问题描述:

The most important thing about cotton in history is __part that is played in__Industrial Revoluton.
A.* *B.the *C.the the D.a the

.因part后面有一定语从句修饰,是特指,用the;又因为“工业革命”是由普通名词构成的专有名词,所以前面也要用the.
选C