Answer: Option 'c' is correct.
Explanation:
Since we know that
A square is a quadrilateral whose all sides are equal and all angles are equal too.
So, A square is equilateral.
A square is equiangular both.
Since a square is also a parallelogram.
But we need the statement which best describes a square.
So, Option 'c' is correct., i.e. A square is equiangular and equilateral.