Which of the following three elements have filled outermost shells?

A

Magnesium (mg), Helium (He), Neon (Ne)

B

Magnesium (mg), Calcium (ca), Barium (Ba)

C

Lithium (Li), Sodium (Na), Potassium (K)

D

Helium (He), Neon(Ne), Argon (Ar)