This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Drug Abuse, Subject name: Forensic Medicine
Which assay is most likely to detect cocaine metabolites? 
Select and explain. 
A. Semen, B. Saliva, C. Hair, D. Urine
D: Urine
Answer: D: Urine 
Explanation: Urine- All the listed body fluids are used to detect cocaine use, except for semen.- Blood and saliva will provide the best level of current usage, while urine assay will detect use over the preceding several days.- Hair analysis can reveal the drug over weeks or months, but has little clinical applicability. - Benzoylecgonine - major metabolite of cocaine, can usually be detected in urine for 48 to 72 hours after cocaine use