Answer: option a. 360 °.
Explanation:
The exterior angles of simple polygons add up 360°.
That is so because making the route of the exterior angles one by one takes you to make a complete revolution (turn), which as we know is 360 °.
You can see that if you draw any polygon and mark its exterior angles and translate all the segments (keeping the angles) to a common vertex. There you will see the angles cover all the circle, so the sum of the angles is 360°.