Correct option (c)
Explanation :
Phenols are much more acidic than alcohols, due to the stabilisation of phenoxide ion by resonance.
-NO2 is the electron withdrawing group and helps in stabilizing the negative charge on the oxygen hence equilibrium shifts in forward direction and more H+ remove easily. Hence, it is most acidic.
-CH, is the electron donating group. Hence electron density increases, on the oxygen and destabilizes the product. Thus, equilibrium shifts in backward direction.
