Mr. Chopra cautioned ( ) adopting the plan.

A. along

B. to

C. at

D. Against

【答案】D。短语考察。Caution sb for sth“因…警告某人”，caution sb to do sth“警告某人不要干某事”，caution against “提防、警告、警惕”。句中caution后没有sb，所以D选项正确。