This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other Key Definitions & Concepts, Subject name: Social & Preventive Medicine
Secondary attack rate reflects ------ of a disease:- 
Select and explain. 
A. Severity, B. Communicability, C. Fatality, D. Virulence
B: Communicability
Answer: B: Communicability 
Explanation: Secondary attack rate = Primary case is excluded from both the numerator and denominator. It determines the communicability of the disease.