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
Severity of a diseases is measured by: 
Select and explain. 
A. Case fatality rate, B. Proportional mortality rate, C. Relative risk, D. Attributable risk
A: Case fatality rate
Answer: A: Case fatality rate 
Explanation: None