A study is being done to test the effects of temperature on the number of microbial colonies. Four different incubators are set up, each at a different temperature with one culture plate in each. Each plate has the same nutrient content, pH, and are inoculated with microorganism samples from the same source. At the end of the experiment, the number of colonies on each plate is counted. What is the independent variable

The correct answer is - the different temperatures of incubators.

Explanation:

An independent variable is a variable in a study or research which is manipulated or changed to check or find the effect on the dependent variable. The independent variable is the only factor that changes in research while other factors remain constant that can affect the result in the study.

In this case or study, there is the only factor that is manipulated is the temperature of incubators is manipulated to see the effect of temperature on the number of microbial colonies. Thus, the different temperatures of incubators is the independent variable here.

it would be c. xylem.