Answer:
4. A rectangle is a square
Explanation:
A rectangle can be a square, but not always. A rectangle has 2 pairs of parallel sides, 2 pairs of congruent sides, and 4 right angles. Squares have 2 pairs of parallel sides, 4 congruent sides, and 4 right angles. So, the difference between the two is that adjacent sides are not necessarily congruent in rectangles, but they are in squares. This means that some rectangles can be a square. If a rectangle has all congruent sides, then it is a square. On the other hand, some rectangles do not have all congruent sides, and thus are not squares.