What type of test is used to evaluate a suspect’s impairment due to drugs?

The selection of psychophysical tests as the correct answer highlights their specific relevance in assessing a suspect's impairment due to drug use. Psychophysical tests are designed to evaluate an individual’s physical and mental coordination, including their ability to perform tasks that require various cognitive functions, such as balance, attention, and reaction time. These tests directly correlate with the impairing effects that drugs can have on motor skills and cognitive processes.

These tests are typically conducted in a controlled environment and may include tasks such as walking a straight line, standing on one leg, or following a specific set of instructions. The results of these tests provide valuable insights into the degree of impairment, which is critical for law enforcement and legal proceedings.

The other options, while they may involve evaluations of a suspect's condition, do not specifically focus on impairment due to drug use. Medical examinations are broader assessments that can encompass a variety of health issues, field sobriety tests may include psychophysical components but are not exclusively focused on drug impairment, and cognitive assessments tend to focus more on mental capacity rather than direct impairment caused by substance use. Each of these alternative methods may lack the targeted criteria that psychophysical tests provide in the context of assessing drug-related impairment.