To prove that quadrilateral ABCD is a parallelogram, one key property that needs to be satisfied is that the diagonals bisect each other. In this case, point E is the point of intersection of diagonals AC and BD.
For diagonals to bisect each other, the lengths of segments EB and ED must be equal:
EB must be the same length as ED.
Thus, the correct response is:
EB must be the same length as ED.