The energy of an electron in a hydrogen atom is determined solely by its :

The energy of an electron in a hydrogen atom is determined solely by its principal quantum number.

The primary quantum number n value that best describes the energy state of an electron of a hydrogen atom is what determines the energy of the electron. Where the quantization of the energy levels is done by the quantum number n=1,2,3,… They therefore represent discrete energy values proportional to 1n2.

Hence, option A is correct.