What is the biconditional statement of the following conditional statement? "If a polygon has five sides, it is a pentagon."

Question

What is the biconditional statement of the following conditional statement?

"If a polygon has five sides, it is a pentagon."

1. If a polygon does not have five sides, then it is not a pentagon. 
2. If a polygon is not a pentagon, it does not have five sides. 
3. If a polygon is a pentagon, then it has five sides. 
4. A polygon has five sides if and only if it is a pentagon.

Answer 1

4 is the correct answer choice. P if and only if Q.