Answer:
Option: C is the correct answer.
C The polygon is regular.
Explanation:
Regular Polygon--
A polygon is said to be regular if each of it's side are of equal length and each of it's angle are of equal measure.
i.e. it is a equilateral and equiangular.
Hence, the polygon with n sides has rotational symmetry of:

i.e. If the n-sided polygon rotates 360° about its center, P. The image coincides with its preimage n times during the rotation.
Hence, the answer is:
option: C