A Group of Investigators Is Studying the Relationship Between a Particular

A group of investigators is studying the relationship between a particular 5-lipoxygenase genotype and atherosclerosis.  A random sample of patients from a local university hospital is invited to participate in the study.  Blood samples for leukocyte genotyping are obtained, and ultrasonography to assess carotid intima-media thickness (CIMT) , a marker of atherosclerosis, is performed.  Results show that the particular 5-lipoxygenase genotype is associated with abnormally increased CIMT, a predisposition to atherosclerosis.  Which of the following best describes this study design?

A) Case-control study
B) Cross-sectional study
C) Prospective cohort study
D) Randomized clinical trial
E) Retrospective cohort study