Correct option is A
Given:
A pair of parallel lines is intersected by a transversal.
1 and 2 form a pair of alternate interior angles.
Concept:
When two parallel lines are intersected by a transversal, alternate interior angles are congruent. This means that if
1 and2 are alternate interior angles, then:
=
Solution:
= we can conclude that:
Thus, the measure of is





