The 2s Orbital Calcium Is More Stable Than the 2p

The 2s orbital calcium is more stable than the 2p orbital even though the 2p orbital has its maximum electron density closer to the nucleus. The reason for this higher stability is

A) calcium's valence orbitals have n = 4.
B) the 1s orbital screens the 2p orbital more than the 2s orbital.
C) the 2s orbital has more electron density closer to the nucleus than the 2p orbital.
D) calcium is an exception to usual trends.
E) all s orbitals are more stable than p orbitals.