To prove that quadrilateral ABCD is a parallelogram, Valentina can use the property that the diagonals of a parallelogram bisect each other. She already has the lengths of segments AE and BE, and to proceed, she needs to show that the segments connecting the other sides also bisect at point E.
The correct choice from the options you provided is:
Valentina will also need to show that segment CE≈2.9 units and segment DE≈3.8 units. This will show that sides AC and BD bisect each other, which proves that ABCD is a parallelogram.
This option directly aligns with the necessary information needed to demonstrate that the diagonals bisect each other, which is a fundamental condition for a quadrilateral to be classified as a parallelogram.