Reflection laws in parallel mirrors Steps:

• Angle POQ = 45° is the angle between incident ray PO and mirror PQ at O, so angle of incidence on PQ is 90° - 45° = 45°.
• By law of reflection, angle of reflection on PQ is 45°, so reflected ray (part of QR) leaves at 45° to normal.
• Mirrors PQ and Y are parallel, so the angle between QR and normal to Y equals 45°.
• Thus, angle of incidence of QR on Y is 45°; RS parallel to PQ confirms the symmetric geometry.

Why D is correct:

• In parallel mirrors, incidence angle equals reflection angle from first mirror, which is 45° by the given POQ.

Why the others are wrong:

• A: Angle between PO and QR is 180° - 2×45° = 90°, not 45°.
• B: Angle between QR and RS is 180° - 2×45° = 90°, not 180°.
• C: 60° contradicts the 45° incidence derived from POQ.

Final answer: D