This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
Zero dose of Polio vaccine in which is give - 
Select and explain. 
A. Before giving DPT, B. At birth, C. When child is having diarrhoea, D. When child is having Polio
B: At birth
Answer: B: At birth 
Explanation: None