Answer:
C. Rhombus.
Explanation:
A rhombus is quadrilateral who each pair of opposite side are parallel and congruent and whose each diagonal is perpendicular to the other diagonal, which bisectors it.
In the cases of rectangle, parallelogram and trapezoid, diagonals are not perpendicular to each other. In the case of the trapezoid, only one pair of sides are parallel.
In consequence, right answer is C.