Geometry

Question Analysis:
This problem examines reflection properties and coordinate analysis after transformation, focusing on negative y-coordinates.

Key Concept Explanation:
Reflection across y = -x follows the transformation (x, y) → (-y, -x).
We need to identify which transformed points have y < 0.

Step-by-Step Solution:
Transform each vertex:
P(3,0) → P'(0,-3) → y = -3 (negative)
Q(0,4) → Q'(-4,0) → y = 0 (non-negative)
R(-2,-1) → R'(1,2) → y = 2 (positive)
Check for negative y-coordinates:
Only P' has y < 0

Option Analysis:
A. Correct (only P' has y = -3)
B. Incorrect (Q' has y = 0...