Chemistry · Chemical Bonding

Option A is correct as Cl has the highest E.A in its group. Although Fluorine is expected to have the highest E.A but due to its small size and large electron density there are electron-electron repulsions and hence some energy is used in overcoming those repulsions. Thus the order of E.A becomes; I<Br<F<Cl. All other options are incorrect.

This is the correct order of increasing electron affinity as explained. 

This is incorrect because bromine does not have the greatest electron affinity, and neither electron affinity of chlorine is less than fluorine. 

This is incorrect because the electron affinity of fluorine is higher than bromine. 

This is the incorrect option as iodine has the least electron affinity among all.