A quadrilateral ABCD has four right angles. The diagonals are perpendicular.?

[ruddy]

Based on the given properties of the quadrilateral ABCD, which of these is a valid conclusion?
Answer
A. Quadrilateral ABCD must be a square.
B. Quadrilateral ABCD must be a rectangle.
C. Quadrilateral ABCD must be a square or a rectangle.
D. Quadrilateral ABCD must be a rectangle or a rhombus.

[kirklin]

D I suppose

[kendrix]

The fact that the quadrilateral has four right angles says immediately that it is a rectangle or a square. If the diagonals are perpendicular, then each diagonal will bisect each right angle. This means that each side of the quadrilateral will have the same length, hence, the figure is a square.

[ricki]

D. Quadrilateral ABCD must be a rectangle or a rhombus since these shapes have the common properties.

Good luck!