90 counterclockwise rotation.
Look at the shapes. When compared to C, shape D looks like it's rotated to the left 90°. This "rotation to the left" is called counterclockwise rotation.
Think about a clock. which way does a clock hand move?
It rotates to the right. This is clockwise.
So, if something is rotated to the left, it would be "counterclockwise."
Hope this helps.
