AB A, B, with, \overleftrightarrow, on top is parallel to \overleftrightarrow{DE}
DE
D, E, with, \overleftrightarrow, on top.

Alicia noticed that:
\angle \maroonD{w} \cong \angle \blueE{x}∠w≅∠xangle, start color #ca337c, w, end color #ca337c, \cong, angle, start color #0c7f99, x, end color #0c7f99
\angle \goldE{y} \cong \angle \blueE{x}∠y≅∠xangle, start color #a75a05, y, end color #a75a05, \cong, angle, start color #0c7f99, x, end color #0c7f99
Note: Alicia used the following theorems:
When a transversal crosses parallel lines, alternate interior angles are congruent.
Vertical angles are congruent.
What theorem can Alicia prove using these congruent angles?
Choose 1
Choose 1

(Choice A)
A
When a transversal crosses parallel lines, corresponding angles are congruent.

(Choice B)
B
Angles that form a linear pair are complementary.

(Choice C)
C
When a transversal crosses parallel lines, same-side interior angles are congruent.

(Choice D)
D
When a transversal crosses parallel lines, alternate exterior angles are supplementary.