Answer: C. gains electrons.
Step-by-step explanation:
- Octet rule states that "it is the tendency of the atom to have eight electrons in its outermost valence electron shell".
- Nonmetals obey octet rule by gaining electrons to its outermost valence electron shell.
- For example: Cl which has 17 electron and its electronic configuration is 2,8,7 and it gain electron to have 8 electrons in its outermost electron shell to form Cl⁻ with electronic configuration of 2,8,8.