Final answer:
The magnesium ion (Mg²⁺) has the same electron configuration as the noble gas neon (Ne), due to the loss of two valence electrons from magnesium. Option C is correct.
Step-by-step explanation:
The magnesium ion Mg²⁺ has an electron configuration that matches the nearest noble gas. When a magnesium atom (Mg) loses two electrons, it becomes a magnesium ion (Mg²⁺) and achieves a stable noble gas electron configuration.
In the case of the magnesium ion Mg²⁺, it is isoelectronic with the nearest noble gas, which is neon (Ne). Therefore, Mg²⁺ has the same electronic structure as neon, not magnesium (Mg), carbon (C), or argon (Ar). The two electrons lost are from the 3s subshell, which magnesium typically occupies beyond the neon core.