Remember that a rotation about the origin of 90° counterclockwise is given by the rule:
[tex](x,y)\rightarrow(-y,x)[/tex]If this rule is applied to the point W, we get W':
[tex]W(-13,9)\rightarrow W^{\prime}(-9,-13)[/tex]Therefore, the rotation that was performed is a 90º counterclockwise rotation.
Then, the answer is option C.