The correct response is:
"Since the sum of angle measures in a triangle is 180°, the third angle pair must have the same measure and are thus congruent. Because all three corresponding interior angles of the triangle are congruent, the triangles are similar by the definition of similarity."
This is based on the Angle-Angle (AA) similarity criterion, which states that if two angles of one triangle are congruent to two angles of another triangle, then the triangles are similar.