We have to find the properties of the angles of the parallelogram that are mantained even when the gate is moved.
A. TRUE. A and C are congruent and B and D are congruent.
B. FALSE. A and B are not congruent (only when it forms a square).
C. FALSE. The segments are not parallel.
D. TRUE. The lengths are equal independent of the movement of the gate.
Answer: A and D.