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In quadrilateral PQRS, sides PS and QR have equal length and sides PQ and RS are parallel to each other. Point X is the intersection of the diagonals PR and QS. Which of the following conclusions must be true?

A) $\triangle PXQ\cong\triangle RXS$

B) $\triangle SPR\cong\triangle RQS$

C) $\triangle SPQ\cong\triangle QRS$