Answer
C. lose these two electrons and become a positively charged ion
Work Step by Step
Magnesium is number 12, so it also has a stable shell when the octet rule is satisfied. When the outer shell is not filled, the electrons in these shells react with other atoms in an attempt to satisfy the octet rule, thereby leading to the formation of other compounds. Since Magnesium has only two electrons in its outer shell it is reactive and wants to get rid of those electrons to go down to a more stable outer shell.
