c
As the atomic size increases down the group, electron affinity generally decreases as the effective nuclear charge decreases. But in group 17 the order of electron affinity is: \(At < I < Br < F < Cl\)

Here, fluorine has a lower electron affinity than chlorine this is due to the small size of fluorine, the electron repulsion will be high between the valence electron and the incoming electron as compared to that in chlorine. Thus, \(Br < Cl\) is correct.