Question

a chemical test is used to measure
reaction time
blood alcohol content
vision
driving ability

Explanation:

A chemical test related to measuring substances in the body. Blood alcohol content (BAC) is measured via chemical tests (like breathalyzer or blood tests) that detect alcohol concentration. Reaction time, vision, and driving ability are assessed through non - chemical methods (e.g., timing tasks, eye exams, driving simulations). So the correct option is the one related to blood alcohol content.

Answer:

Blood alcohol content (the option labeled "Blood alcohol content" in the list)