which of the following is an equivalent transformation to rotation of an object clockwise 90°?

1. rotation about the origin of 90° counterclockwise.
2. Rotation about the origin of 270° clockwise
3. Rotation about the origin of 270° counterclockwise.
4. Rotation about the origin of 180° counterclockwise.

The correct answer is 1. rotation about the origin of 90° counterclockwise.