Characteristic X-Rays Can Be Produced by Bombarding Targets with Electrons

Multiple Choice

Characteristic x-rays can be produced by bombarding targets with electrons.These x-rays occur when:

A) electrons from higher shells fill the vacant lower shell.
B) electrons fill the vacant valence shell.
C) photons are emitted with energies on the order of 103 eV.
D) photons are emitted with wavelengths on the order of 103 nm.