Correct Option :- (B)
Explanation :-
+I effect decreases the acidic character of carboxylic acid and –I effect increases the acidic character. Since the electronegativity order of 'C' attached to carboxylic acid is sp > sp2 > sp3, hence the order is I > II > III > IV.
II is more acidic than III since the electron donating group is attached to benzene ring.
