Three different compounds have the same molecular formula, C2H2F2; call them A, B, and C. Compound A has a dipole moment of 2.42 D, compound B has a dipole moment of 1.38 D, and compound C has a dipole moment of 0 D. All three compounds react with hydrogen, H2:
C2H2F2 + H2 → C2H4F2
Compound A gives product D (molecular formula C2H4F2), compound B gives product E (same molecular formula, C2H4F2, but different from product D), and compound C gives product D. Identify the structural formulas of compounds A, B, and C.