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: Dental
Denominator while calculating the secondary attack rate includes: 
Select and explain. 
A. All the people living in next fifty houses, B. All the close contacts, C. All susceptibles amongst close contact, D. All susceptibles in the whole village
C: All susceptibles amongst close contact
Answer: C: All susceptibles amongst close contact 
Explanation: None