Ainsley wanted to know if caffeine impacted the rate a mouse learned a maze. He tested two groups of mice and timed them as they attempted to learn the maze. Lab group A received 5 mL of caffeine with their 20 g of grain. Lab group B received 20 g of grain without caffeine. Which is Ainsley's independent variable?

Caffeine

Explanation:

In every study, there must be an independent variable and a dependent variable. The independent variable is being manipulated and its effect on the dependent variable is evaluated.

In this study, the independent variable is the administration of caffeine. Its effect on a rat's ability to learn the maze (dependent variable) is evaluated in the study.