Which molecular formula is also an empirical formula?

A.     \({\text{PC}}{{\text{l}}_{\text{3}}}\)

B.     \({{\text{C}}_{\text{2}}}{{\text{H}}_{\text{4}}}\)

C.     \({{\text{H}}_{\text{2}}}{{\text{O}}_{\text{2}}}\)

D.     \({{\text{C}}_{\text{6}}}{{\text{H}}_{{\text{12}}}}{{\text{O}}_{\text{6}}}\)

A