In quadrilateral ABCD, sides AB and DC have equal length and are parallel to each other. Point P is the intersection of the diagonals AC and BD. How many pairs of congruent triangles are in the figure?

Which of the following transformations will make coincide with ? a. counter-clockwise rotation 90º about a, followed by a translation 5 units to the right b. translation 5 units to the right, followed by a reflection across the y-axis c. translation 5 units to the right, followed by a reflection across the x-axis d. translation 1 unit up and 5 units to the right, followed by a reflection across the x-axis