Answer: Option (D) is the correct answer.
Explanation:
Atomic number of chlorine is 17 and its electronic distribution is 2, 8, 7.
So, in order to attain stability it tends to gain one electron from a donor atom. Therefore, a chlorine ion is formed as .
As it gains only one electron that is why, -1 charge occurs.
Whereas Ar is a noble gas with atomic number 18. As it has completely filled octet so it will be unreactive in nature as it is already stable.
Similarly, He is also a noble gas so it is unreactive in nature.
Atomic number of boron (B) is 5 with electronic distribution 2, 3. So, in order to attain stability it needs to lose 3 electrons.
Thus, we can conclude that Cl is the atom which tends to gain 1 valence electron from another atom in order to become stable.