Determine if the biconditional is true. If false, give a counterexample. "A figure is a square if and only if it is a rectangle."

A. The biconditional is true.

B. The biconditional is false. A rectangle does not necessarily have four congruent sides.

C. The biconditional is false. All squares are parallelograms with four 90° angles.

D. The biconditional is false. A rectangle does not necessarily have four 90° angles.