This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable diseases, Subject name: Social & Preventive Medicine
The most heat sensitive vaccine i s- 
Select and explain. 
A. Measles, B. Hepatitis B, C. DPT, D. OPV
D: OPV
Answer: D: OPV 
Explanation: - non stabilised OPV is highly heat sensitive and should be stored at -20degC in a deep freeze until used. - a primary problem of OPV is the instability of vaccine at high ambient temperature. Reference : Park's textbook of preventive and social medicine, 23rd edition, pg no:207 <\p>