Question

max is testing how caffeine affects concentration. which variable is the independent variable? concentration, because it is manipulated by max caffeine, because it is manipulated by max caffeine, because it is measured by max concentration, because it is measured by max

Explanation:

In an experiment, the independent variable is the one that the experimenter manipulates. Max is testing how caffeine affects concentration, so Max manipulates the amount or presence of caffeine.

Answer:

B. Caffeine, because it is manipulated by Max