This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunization, Subject name: Pediatrics
A full course of immunization with 3 doses of tetanus toxoid, confers immunity for how many years? 
Select and explain. 
A. 5, B. 10, C. 15, D. 20
B: 10
Answer: B: 10 
Explanation: b. 10(Ref: ZAP 157, Nelson's 20/e p 1255> Ghai 8/e p 196-197)In individuals who have completed primary & booster vaccination with DTP, TT boosters every 10 yrs provide sufficient protection.