Which carbocation is the most stable ?

Given data: It is given to find the most stable carbocation from the following.

Explanation:

On comparing the groups that are attached to the ring, CH₃, OH, Cl and NO₂, we can identify that out off them OH, Cl and NO₂ are all electron-withdrawing groups, unlike CH₃, which is an electron-donating group since Carbon is more electronegative than hydrogen, thus it donates electrons (as it has a higher proton number:atomic radius ratio, so it has a greater tendency to attract a bonding pair of electrons), thus making it most stable among the given compounds.

Hence, the correct option is option (A)   .