1. The problem asks to identify which quadrilaterals have diagonals that bisect each other at 90 degrees. 2. Let's analyze each option: - A Trapezium: Generally, the diagonals of a trapezium do not bisect each other, and they do not intersect at 90 degrees. - B Rectangle: The diagonals of a rectangle bisect each other but are equal in length and intersect at 90 degrees only if the rectangle is a square. - C Rhombus: The diagonals of a rhombus always bisect each other at 90 degrees. - D Square: A square is a special type of rhombus and rectangle where the diagonals bisect each other at 90 degrees. 3. Therefore, the quadrilaterals whose diagonals bisect each other at 90 degrees are the Rhombus and the Square. 4. Summary: - Trapezium: No - Rectangle: No (unless it is a square) - Rhombus: Yes - Square: Yes Final answer: C Rhombus and D Square.