Answer:
Reason 1: Given
It is already given that QM ║ OP
Reason 2: Alternate interior angles
Since ∠MQN and ∠PON are alternate interior angles, they are congruent.
Reason 3: Vertical angles
∠MNQ and ∠PNO are vertically opposite angles and hence, due to that, equal.
Reason 4: AA postulate
2 Angles of the triangle are congruent. which makes the triangle congruent by AA (Angle-Angle) Postulate.