What is the missing step in the given proof? a.  ∠pqc  and  ∠acp  are supplementary by the linear pair theorem. b.  for parallel lines cut by a transversal, corresponding angles are congruent, so ∠acb  ≅  ∠pcq. c.  ∠ocp  ≅  ∠bcd  by the vertical angles theorem. d.  for parallel lines cut by a transversal, corresponding angles are congruent, so ∠ocp ≅  ∠abc. e.  for parallel lines cut by a transversal, corresponding angles are congruent, so ∠oca  ≅  ∠cbd.