Answer:
3s orbital
Explanation:
3s is the outermost orbital of magnesium and it loses electron from it, it doesnt even have 4f, 5p or 3d orbitals.
Magnesium representation : 1s²2s²2p⁶3s².
therefore, to become Mg2+ ion Magnesium losses electron from its 3s orbital to form 1s²2s²2p⁶.
therefore option C is correct.
hope this helps you.
