1. The problem asks to identify which angle is the alternate interior angle to angle 1 when three parallel lines are cut by a transversal. 2. Alternate interior angles are pairs of angles that lie between the parallel lines on opposite sides of the transversal. 3. Given angle 1 is at the top intersection on the left side of the transversal, its alternate interior angle must be on the opposite side of the transversal and between the parallel lines. 4. From the description, angle 4 is located at the middle intersection on the bottom right, which fits the position of an alternate interior angle to angle 1. 5. Therefore, angle 4 is the alternate interior angle to angle 1. Final answer: angle 4