This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Biostatistics, Subject name: Social & Preventive Medicine
Herd immunity is not seen in- 
Select and explain. 
A. Poliomyelitis, B. Measles, C. Diphtheria, D. Tetanus
D: Tetanus
Answer: D: Tetanus 
Explanation: .