Answer: c) -3
Explanation: The charge on an ion equals to the number of electrons an atom gain or lose to get its nearest noble gas like electron configuration.
If an atom has 5 valence electrons then it would accept three electrons to complete 8 valence electrons in its valence shell.
8-5 = 3
Since, the atom has to accept 3 electrons, the usual charge on an ion formed will be -3.
(The charge is negative if the electrons are accepted and its positive if the electrons are lost.)
So, the correct choice is c) -3.
For example, N has 5 valence electrons, the usual charge on its ion is -3 as it accepts three electrons to complete its octet.(Neon like electron configuration).