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 explanation accurately describes why two triangles are similar when two pairs of corresponding angles are congruent. Because the sum of angles in a triangle is always 180°, the third pair of angles must also be congruent, confirming that all corresponding angles are congruent, which leads to similarity by the Angle-Angle (AA) similarity criterion.