Which best explains if quadrilateral wxyz can be a parallelogram?

wxyz can be a parallelogram with one pair of sides measuring 15 mm and the other pair measuring 9 mm.
wxyz can be a parallelogram with one pair of sides measuring 15 mm and the other pair measuring 7 mm.
wxyz cannot be a parallelogram because there are three different values for x when each expression is set equal to 15.
wxyz cannot be a parallelogram because the value of x that makes one pair of sides congruent does not make the other pair of sides congruent.