c
(c) Due to the presence of electron rich methoxy group \((+I)\) at \(p-\)position the polarity increase on \(C-X\)  bond by which it becomes more reactive towards nucleophillic attack of ethanol, \(p-\) nitro and chloro are electron deficient group decrease the polarity of  \( C-X\) bond.

Hence by them it become difficult to react with ethanol due to less polarity.

Methyl group is less electron rich than methoxy group.