Which of the Following Statements Is the Most Accurate Characteristic

Which of the following statements is the most accurate characteristic of the nested case-control study?

A) A control who is selected early in the study could later develop the disease but cannot be a case in the same study.
B) In nested case-control studies, controls are a sample of individuals who are at risk for the disease at the time each case of disease develops.
C) Controls are randomly chosen from the defined cohort with which the study began.
D) The problems of possible recall bias from conventional case-control studies still remains.
E) Nested case-control studies are often less economical to conduct.