What Is the Energy of the Photon Emitted When an Electron

Multiple Choice

What is the energy of the photon emitted when an electron drops from the $n = 20$ state to the $n = 7$ state in a hydrogen atom?

A) $0.283 \mathrm { eV }$
B) $0.303 \mathrm { eV }$
C) $0.264 \mathrm { eV }$
D) $0.244 \mathrm { eV }$