Answer:
C.
Step-by-step explanation:
The mapping for 90° counterclockwise rotation is ...
(x, y) ⇒ (-y, x)
If we consider how this applies to points X and Y, which both have a y-coordinate of 0 and a negative x-coordinate, (-a, 0), for example, we see it maps to ...
(-a, 0) ⇒ (0, -a)
That is, both points X' and Y' will be on the negative y-axis. The only figure showing this is figure C.
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Comment on the other answer choices
Figures A and D show clockwise rotation. In Figures A and B, the rotation is not about the origin, but is about a different point. (In Figure B, the points easy to consider are the ones on the -x axis, points X and Z. They should appear on the -y axis after rotation, but do not.)
