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
. A case control study is not characterized by - 
Select and explain. 
A. Cases with the disease are compared to controls without the disease -, B. Assessment of past exposure may be blased, C. Definition of cases may be difficult, D. Incidence rates may be computed directly
D: Incidence rates may be computed directly
Answer: D: Incidence rates may be computed directly 
Explanation: None