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
One of the following is known as Tuberculin Conversion Index 
Select and explain. 
A. Incidence of disease, B. Prevalence of infection, C. Incidence of infection, D. Prevalence of disease
C: Incidence of infection
Answer: C: Incidence of infection 
Explanation: None