Geometry

Question Analysis：
This question reflects an entire triangle across the line y = x by transforming all its vertices.
The main focus is applying the coordinate rule to multiple points.

Key Concept Explanation:
To reflect over y = x, apply the rule (x, y) → (y, x) to each vertex of the triangle.
No signs are changed—just the positions of x and y.

Step-by-Step Solution：
Reflect each point:
A(1, 4) → A′(4, 1)
B(3, 2) → B′(2, 3)
C(2, 5) → C′(5, 2)
So, the reflected triangle is A′(4, 1), B′(2, 3), C′(5, 2)

Option Analysis：
A. ✅ Matches all three reflections correctly.
B. Reflected and flipped signs—confused with y = –x.
C. Three point changed differently.
D....