तीन संख्याऐं एक वर्धमान गुणोत्तर श्रेढ़ी, जिसका सार्व अनुपात \(I\) हैं, में है। यदि बीच की संख्या को दुगुना कर दिया जाये, तो नयी संख्याऐं एक समान्तर श्रेढ़ी, जिसका सार्वअंतर \(d\) है, में हैं। यदि गुणोत्तर श्रेढ़ी का चौथा पद \(3 r^{2}\), है, तो \(r^{2}- d\) बराबर 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.