Answer:
rotation of 90 degrees counterclockwise centered at the origin
Explanation:
Just look at one single point of A and what must happen to it to become the corresponding point in B.
Look at point (2, 1) in figure A. Draw a segment from (0, 0) to (2, 1).
The corresponding point in figure B to (2, 1) is (-1, 2). Now draw a segment from (0, 0) to (-1, 2). Look at the relationship between the two segments.
The segment (0, 0) to (2, 1) is perpendicular to the segment (0, 0) to (-1, 2).
The transformation is a rotation of 90 degrees counterclockwise centered at the origin.