Which of the following electronic configuration in the outermost two shells is characteristic of the alkaline earth metals?
A. `(n-1)s^(2)p^(6),ns^(2)underline((n-1)s^(2)p^(6))underline(ns^(2))`
B. `(n-1)s^(2)p^(6)d^(10),ns^(2) underline((n-1)s^(2)p^(6)d)underline(ns^(2))`
C. `(n-1)s^(2)p^(6),ns^(2)np^(1)underline((n-1)s^(2)p^(6)ns^(2)np^(1))`
D. `(n-1)s^(2)p^(6),ns^(2)np^(2)underline((n-1)s^(2)p^(6)ns^(2)np^(2))`.