If you were conducting an experiment with pepsin which has an optimal enzymatic activity at pH 2.3 what buffer would be the best choice

The answer should be c.

There is one s orbital, and there are three p orbitals, five d orbitals, and seven f orbitals. thus, the answer is b. do not confuse the number of orbitals in a subshell with the number of electrons the subshell can hold. each orbital can hold two electrons, so the capacity of an nf subshell is 14 electrons.

What? i don’t understand