We can’t produce a H-atom by combining electron and proton because binding energy of H-atom is larger as compared to the energy of free electron. Large amount of energy is required so that electron can reach near the proton which is possible when nuclear force (attractive) acts between e and p which is only possible when energy is conserved so option (c) & (d) will be wrong. Also in this process without simultaneously releasing energy in the form of radiation, an electron and a proton cannot combine to produce a H-atom

Therefore option (a) & (b) are correct.