Which of the following aryl chlorides reacts fastest with sodium methoxide in methanol on moderate heating, by the addition-elimination (SNAr) pathway?

SNAr needs a strongly electron-withdrawing group ortho or para to the leaving group so that the negative charge of the intermediate can be delocalised. Only the nitro compound has such a group. The methyl and methoxy groups donate electrons and chlorobenzene has no activation. The nitro compound reacts fastest.