Answer:
B. -75
Explanation:
Consider segments AC and A'C'. Point A' is clockwise from point A by an amount less than 90°. Positive angles are measured counterclockwise, so this suggests the angle of rotation is about -75°.
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In the attached, we have used the invariant point on segments AC and A'C' as the vertex of the angle we want to measure. The angle between the lines appears to be about 75°, matching the answer choices.