Answer:
It is produced by the energy emitted when the electron falls back to it's ground state.
Step-by-step explanation:
Hydrogen has a single electron that normally will reside in the lowest energy orbital, 1s. That electron may move to a higher energy level if the atom is exposed to outside energy, such as heat or light. It may move to any of the higher energy orbitals (2s, 2p, 3s, etc.), depending on the amount of energy absorbed. At some point, the excited electron will return to the 1s orbital. The energy difference between the two orbitals will be released as light energy having a wavelength consistent with the energy loss/difference.
Since there are several orbitals to which the electron could move, there are several wavelengths produced in the emission spectrum.