The researchers compute the rate of foot ulcers in diabetic patients versus non-diabetic patients

Researchers perform a study on foot ulcers caused by diabetes. They collect patients of foot ulcers and divided them into a group of patients with diabetes and another group of non-diabetic patients. The researchers compute the rate of foot ulcers in diabetic patients versus non-diabetic patients.

This study is considered:

A-Case-control study
B-Cohort study
C-Longitudinal study
D-Cross-sectional study
E-Double-blind study