The hybrid orbital set used by the central atom in no3- is

The hybrid orbital set used by the central atom in NO3- is sp2. Hybrid orbitals results from a model which combines atomic orbitals on a single atom in means that lead to a new set of orbitals that have geometries appropriate to form bonds in the directions predicted by the VSEPR model. 

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.