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
Regarding point source epidemic true -a) Rapid rise and fallb) Only infectious causec) Explosived) ↑ secondary attack ratee) No secondary wave 
Select and explain. 
A. ae, B. edb, C. ace, D. bd
C: ace
Answer: C: ace 
Explanation: None