Step 1: Concept
Schedule P of the Drugs and Cosmetics Act specifies the life period and storage conditions for various drugs to maintain their potency.
Step 2: Meaning
Storage conditions range from "cool places" to specific sub-zero temperatures for sensitive biologicals.
Step 3: Analysis
Erythromycin (A) is generally stored in a cool place (A-I) . d-Panthenol (B) must be protected from light (B-II). Polio vaccine (C) is highly heat-sensitive and must be stored at $0^{\circ}C$ to $-20^{\circ}C$ (C-III). Insulin (D) must be kept refrigerated at a temperature between $2-8^{\circ}C$ (D-IV).
Step 4: Conclusion
The correct sequence is A-I, B-II, C-III, D-IV.
Final Answer: (B)