Answer:
Option A.
Explanation:
Given: QRST is a parallelogram and M is the intersection of diagonals.
We know that opposite sides of a parallelogram are parallel and equal.
In △QMR and △SMT,
(Alternate interior angles)
(Definition of parallelogram)
(Alternate interior angles)
Two corresponding angles and included sides are congruent.
(ASA postulate)
Hence, the correct option is A.