What is the electron configuration of aluminum?
A1s22s22p63s23p1
B1s22s22p63s3
C1s22s23s23p64s1
D1s22s22p63s23d1
A1s22s22p63s23p1
B1s22s22p63s3
C1s22s23s23p64s1
D1s22s22p63s23d1