Which figure has rotational symmetry? Question 21 options: a) butterfly b) chalkboard c) half of an apple

B) Chalkboard.

Step-by-step explanation:

Ok, so basically you need to know what rotational symmetry is. Rotational symmetry is the property a shape has that when rotated some amount of degrees less than 360, it looks the same as it was without being rotated at all.  

So, basically it means that the figure can be rotated and it will look as though it hasn't been rotated at all.

Starting off with the butterfly, it is clear that even when rotated it will never look the same as it was without being rotated (you can click on the image rotation function to see this).

Next, looking at the chalkboard, it is obvious that when rotated 180 degrees, it will look the same as it looked without being rotated (click the rotate image button twice). So, this will be our answer.

step-by-step explanation: