Answer:
C. 18°
Step-by-step explanation:
The order of symmetry (n) is the number of times a shape fits onto itself during a complete turn through 360°.
The angle of rotational symmetry (θ) is the smallest angle through which the shape must be rotated to coincide with itself.
To find the angle, you divide the number of degrees in a circle by the order of symmetry.
θ = 360/n
= 360/20
= 18°
