Answer:
D. Angle 1
Explanation:
Angle 1 is equivalent to angle 4 because they are opposite angles. Angle 3 and angle 6 are right angles, so they are equivalent, and 2 and angle 5 are equivalent. Since 3 and 6 along with 2 and 5 are congruent angles 4 and 1 are the only other angles that can be congruent.