दो ऊर्ध्वाधर समान्तर दर्पण \(\mathrm{A}\) व \(\mathrm{B}\) एक दूसरे से \(10 \mathrm{~cm}\) की दूरी पर स्थित हैं। दर्प्रण \(A\) से \(2 \mathrm{~cm}\) की दूरी पर एक बिन्दु वस्तु \(O\) स्थित है। दर्पण \(A\) के पीछे द्वितीय निकटतम प्रतिबिम्ब की दर्पण \(A\) से दूरी_____________\(\ldots \mathrm{cm}\) है।

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.