Cook was a strict but good captain who usually took care of the sailors on his ship.A.

问题补充：

Cook was a strict but good captain, who, usually, took care of the sailors on his ship.

A. the one

B. one

C. that

D. this

答案：

A. the one

(答案→)B. one

C. that

D. this

解析：考查同位语及定语从句。one 做a strict but good captain的同位语，并且做后面定语从句的先行词，句意：库克是一名严格而又和蔼的队长，他经常照顾他船上的船员们。所以选B。