Question: Which of the following is NOT a characteristic of a regular polygon?

Options:

1. All sides are of equal length.
2. All interior angles are equal.
3. It can have an odd number of sides.
4. It can be concave.

Correct Answer: It can be concave.

Solution:

A regular polygon is defined as a polygon with all sides and angles equal, and it cannot be concave; it must be convex.