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: Unknown
The immunity responsible for to control epidemic spread of a pathogen 
Select and explain. 
A. Innate immunity, B. Active acquired immunity, C. Herd immunity, D. Passive natural immunity
C: Herd immunity
Answer: C: Herd immunity 
Explanation: Herd immunity-
Overall immunity of a community to a pathogen
If Herd immunity is good- chance of epidemic is less
Eradication of a communicable disease- depends on good Herd immunity
Provided by mass vaccination by live vaccination to all individual at same time.