Answer
C. It becomes a cation.
Step-by-step explanation
An atom contains 3 subatomic particles: protons, electrons, and neutrons.
Protons are positively charged, electrons are negatively charged and neutrons do not carry any charge.
An atom has an equal number of protons and electrons.
So if an atom gains electrons, it will have more electrons than protons. Thus, it will carry a negative charge and form an anion.
And if an atom loses electrons, it will have less number of electrons than protons. Thus, it will carry a positive charge and forms a cation.
Therefore, if an atom of sulfur (S) loses an electron, it becomes a cation.
The correct answer is option C. It becomes a cation.