Geometry

Question Analysis:
This question evaluates understanding of how two reflections over intersecting lines combine into a single transformation.

Key Concept Explanation:
Two reflections over lines intersecting at angle θ = rotation by 2θ.
Here, y = x and y = −x intersect at 90∘, so the result is a 180∘ rotation.

Step-by-Step Solution:
First reflection (over y = x): (x, y) → (y, x).
Second reflection (over y = −x): (y, x) → (−x, −y).
This matches a 180∘ rotation.

Option Analysis:
A: Incorrect (would require 45∘ intersection).
B: Correct.
C: Incorrect (translations re...