Answer: Option (C) is the correct answer.
Explanation:
Elements of group 18 are also known as noble gases.
And, noble gases are the gases that have completely filled outermost shells.
For example, atomic number of neon is 10 and its electronic distribution is 2, 8.
As it has completely filled outermost shell hence, it does not need to either gain or lose an electron. Therefore, elements of group 18 are chemically inactive in nature.
Thus, we can conclude that one possible reason for the stability of the noble gas elements is that their outermost shell has the maximum number of electrons that it can hold.