Geometry

Question Analysis:
This question mainly focuses on determining the angle of rotation of a figure around the origin.
The key is to observe the positional relationship between the original figure (the black triangle) and the rotated figure (the red triangle) to figure out the angle of rotation.

Key Concept Explanation:
In the coordinate plane, when a figure rotates around the origin, we can determine the angle of rotation by observing the changes in the coordinates of the points on the figure or the overall orientation change of the figure.
Common angles of rotation include 90°, 180°, 270°, etc., and the position of the figure has distinct characteristics after rotation at different angles.

Step - by - Step Solution:
By observing the black triangle and the red triangle, we can see that the sides of the black triangle are perpendicular to their corresponding sides in the red triangle after rotation.
According to the properties of rotation, this situation corresponds to a 90° clockwise rotation. So the answer is A.

Option Analysis:
Option A: 90° is in line with the characteristics of the figure's rotation, so it is the correct answer.
Option B: A 180° rotation would make the figure centrally symmetric about the origin with the original figure, which does not match the situation in this graph, so it is wrong.
Option C: A 270° clockwise rotation does not match th...