The electron configuration notation for na is:
A. 1s 2 2s 2 2p 6
B. 1s 2 2s 2
C. 1s 2 2s 2 2p 6 3s
D. 1s 2 2s 2 2p 6 3s 2
E. 1s 2 2s 2 2p 5