How does the wave model of electrons orbiting the nucleus account for the fact that the electrons can have only discrete energy values?

(a) Electrons are able to vibrate only at particular frequencies.

(b)When an electron wave is confined, it is reinforced only at particular frequencies.

(c) The energy values of an electron occur only where its wave properties have a maximum amplitude.

(d) The wave model accounts for the shells an electron may occupy, not its energy levels.