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.