The Valence Electron of a Sodium Atom Does Not Sense

The valence electron of a sodium atom does not sense the full +11 of the sodium nucleus. Why not?

A) There are two "non-valence shell" electrons shielding the sodium nucleus from sensing it.
B) There are two inner shells of electrons containing ten electrons shielding the sodium nucleus from sensing it.
C) Since the +11 charge is spread evenly around the entire spherical surface of the nucleus, the actual force of the charge in any given direction is greatly diminished.
D) The distance from the nucleus to the loosely held lone valence electron varies greatly over time. So, the average sense of charge from the nucleus is considerably less than +11.