Answer:
The concentration of the student's sample shows the presence of drug residue in his body. It is found in the form of fluid, for example, in urine samples, which are laboratory-tested and reviewed by a medical officer.
Explanation:
ng/mL (Nanograms per milliliter) is the most commonly used measurement for expressing drug testing cutoff levels and quantitative test results in urine and oral fluid. It is, therefore, the standard unit of measurement of drug fluid in a person's urine.
