What is the right answer?

Option C

Explanation:

In Lewis dot structure the valence electrons are represented as dots around the symbol.

For example,

In hydrogen valence electron is only one it can be represented as,

H·

We know that in covalent bonding atoms share their electron to complete the octet. Thus, their Lewis dot structure would be represented as,

H:H

This is the Lewis dot structure of H₂.

In given atom X their are  2 valence electrons (3s²) thus its Lewis dot structure contain two dots around the symbol.

Option C is correct answer because it has only two dots which actually represent valence electrons.

Other options are incorrect because symbol X has more than two electrons/dots.