For a sample of ground-state phosphorus atoms, which of the following best describes the two peaks that arise from electrons in the n = 3 shell?
a) A taller peak at higher binding energy from the 3p electrons and a shorter peak at lower binding energy from the 3s electrons.
b) A taller peak at lower binding energy from the 3p electrons and a shorter peak at slightly higher binding energy from the 3s electrons.
c) Two peaks of equal height, the 3s peak appearing at lower binding energy than the 3p peak.
d) A single broad peak because the 3s and 3p electrons have nearly identical binding energies and merge into one feature.