The correct answer is C. Mg
Explanation:
Magnesium is one of the 180 chemical elements that are known, this element has an atomic number (number of protons) of 12, and shares features with other elements as similar to calcium, barium and other Earth metals magnesium is a grey solid. Additionally, this element is represented with the symbol Mg that derives from the word Magnesium and it is one of the most common elements not only on Earth but also outside it. According to this, the chemical symbol for magnesium is Mg.
