What is the formula of calcium phosphide?

A.     ${\text{C}}{{\text{a}}_{\text{2}}}{{\text{(P}}{{\text{O}}_{\text{3}}}{\text{)}}_{\text{3}}}$

B.     ${\text{C}}{{\text{a}}_{\text{2}}}{{\text{P}}_{\text{3}}}$

C.     ${\text{C}}{{\text{a}}_{\text{3}}}{{\text{(P}}{{\text{O}}_{\text{4}}}{\text{)}}_{\text{2}}}$

D.     ${\text{C}}{{\text{a}}_{\text{3}}}{{\text{P}}_{\text{2}}}$

D