Which of the following statements would be represented with P ↔ Q?
A). If a quadrilateral has four congruent sides, then it's either a square or a rhombus.
B). If a quadrilateral has four congruent angles, then it's a rectangle.
C). A quadrilateral has four congruent sides and four right angles if and only if it's a square.
D).A quadrilateral with four congruent sides and four right angles is a square.