Given:
RSTU is a parallelogram.
SXT
UXR
SXR
UXT
SEE PICTURE

Answer:
(A)ΔSXT≅ΔUXR
Step-by-step explanation:
It is given that RSTU is a parallelogram, thus
From ΔSXT and ΔUXR, we have
UR=TS (Opposite sides of parallelogram are equal)
SX=UX (Diagonals of parallelogram bisect each other)
RX=TX (Diagonals of parallelogram bisect each other)
Thus, by SSS rule of congruency,
ΔSXT≅ΔUXR
Hence, option A is correct.