What is the formula of magnesium fluoride?

A.     ${\text{M}}{{\text{g}}_{\text{2}}}{{\text{F}}_{\text{3}}}$

B.     ${\text{M}}{{\text{g}}_{\text{2}}}{\text{F}}$

C.     ${\text{M}}{{\text{g}}_{\text{3}}}{{\text{F}}_{\text{2}}}$

D.     ${\text{Mg}}{{\text{F}}_{\text{2}}}$

D