Question

practice it! which of the following is the independent variable (or test variable) in the flu - d12 investigation? the amount of virus killed the exposure to ultraviolet light the temperature of the environment the rate of viral infection

Explanation:

In an investigation, the independent variable is the factor that is deliberately changed or manipulated. In a flu - related investigation, exposure to ultraviolet light can be controlled by the experimenter to see its effect on other factors like virus killing or rate of infection. The amount of virus killed, temperature of the environment, and rate of viral infection are likely to be dependent on other factors and are outcomes that are measured, not manipulated directly.

Answer:

the exposure to ultraviolet light