# Which of the following groups show +M and -I effect?

Which of the following group show +M and -I effect?

(A) $$\ce{-\underset{\underset{\huge O}{||}}{C}-F}$$
(B) $$\ce{-\underset{\underset{\huge O}{||}}{C}-OR}$$
(C) $$\ce{-O^-}$$
(D) $$\ce{-OH}$$

Answer is option D. D is obviously correct, but why not option C? $$\ce{-O^-}$$ has electrons to donate and is electronegative.

• O- is an electron-rich species, which donates its charge to the ring, stringly activating it. It has a very strong +I effect! – The_Vinz Jul 9 at 6:27