According to valence bond theory, which orbitals on n and h overlap in the nh3 molecule?

According to valance bond theory, sp3 on N overlaps with 1s on H.
when we look at the detail of the valance bond theory, according to that, a covalent bond is formed between the two atoms when there is a overlap of half filled valence atomic orbitals of each atom that contain one electron that is unpaired.

Most likely a is the answer - because  you generate   38 atp's but also consume an atp.   each atp gives approx. less than 4 kcal so probably a is the closest answer.