The ship a severe storm was travelling to the west coast of the United States from Korea.

问题补充：

The ship a severe storm was travelling to the west coast of the United States from Korea.

A. was caught in

B. which caught in

C. caught in

D. caught by

答案：

A. was caught in

B. which caught in

(答案→)C. caught in

D. caught by

解析：句意：遭遇严重风暴的这艘船从韩国向西朝美国西海岸航行。这里was travelling是谓语动词，前面需要定语修饰the’ ship，词组“be caught in”遭遇到，所以用过去分词做定语，B项是定语从句，但是缺少was，所以选C。