This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
If a 11 month old child has received two doses of DPT and polio, comes for fuher immunization after 5 months of the last dose, what should be done? 
Select and explain. 
A. Repeat the whole course, B. Repeat the 2nd dose and continue rest of the course, C. Give 3rd dose and continue the course, D. Give only booster dose
D: Give only booster dose
Answer: D: Give only booster dose 
Explanation: Interruption of the schedule with a delay between doses does not interfere with the final immunity achieved. Booster dose is sufficient. Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 134