They were the Boy Scouts ________ to help elderly people cross the streets．

A.whose was the work

B.to whom was the work

C.it was whose work

D.whose work it was

答案及解析： D

解析：

该题考查定语从句的用法。定语从句中的it为形式主语，真正的主语为后面的不定式部分，故答案为D项。