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.