Which is an appropriate use of quantitative testing?

Quantitative testing is designed to provide precise measurements of specific substances or variables in a sample. In this context, measuring blood cholesterol levels is a prime example of quantitative testing because it involves analyzing the concentration of cholesterol in the blood, which can be expressed in numerical terms (e.g., milligrams per deciliter). This kind of testing allows for the monitoring of health conditions, assessment of risk factors for diseases such as cardiovascular disorders, and management of treatment plans.

The other options do not exemplify appropriate uses of quantitative testing in the same way. Checking for the presence of bacteria typically involves qualitative testing methods, such as culture techniques, where the focus is on whether bacteria are present or absent rather than quantifying how many there are. Determining whether a chemical is toxic often requires qualitative assessments or varying methodologies that do not strictly quantify toxicity in numerical terms on their own. Identifying the strain of a virus is primarily a genetic or biochemical identification process, which is more qualitative; while specific viral loads can be quantified, the basic identification does not lend itself readily to a quantification framework without additional context. Thus, measuring blood cholesterol stands out as the most appropriate use of quantitative testing.