Geometry

Question Analysis：
Reverse-engineering problem applying the angle doubling rule.

Key Concept Explanation：
Rotation angle = 2 × mirror intersection angle
Given rotation: 140° → θ = 140°/2 = 70°
Works for any θ < 180°

Step-by-Step Solution：
Set up equation: 2θ = 140°
Solve: θ = 70°
Verify: 2 × 70° = 140° matches given rotation

Option Analysis：
A) Incorrect: Half of correct angle (35° × 2 = 70°)
B) Incorrect: 55° would produce 110° rotation
C) Correct: Matches calculation
D) Incorrect: Exceeds possible range (would require 2...