Which polygon is irregular?

Any polygon that does not have all congruent sides is an irregular polygon. Irregular polygons can still be pentagons, hexagons and nonagons, but they do not have congruent angles or equal sides.

Any polygon that does not have all congruent sides

Explanation:

answer; have joints that fail from excess by early the accumulated effects of unnoticed infections,all of these things are possible for a person born without the ability to feel pain;