Which of the following is an example of a dependent variable?

In the context of scientific experiments, a dependent variable is the factor that is measured or observed in response to changes made to the independent variable. In this case, the time it takes for a reaction to complete is directly affected by the conditions set by the experiment, such as the amount of light, temperature, or type of plant used.

When conducting experiments, researchers typically manipulate one or more independent variables to observe their impact on the dependent variable. Since the time measurement reflects the outcome of these manipulations, it serves as the dependent variable that provides insight into how the reaction behaves under various conditions. The other options listed—like the amount of light, type of plant, and temperature—represent variables that could be controlled or set by the researcher, but they do not capture the result of the experimental changes. Instead, these options can influence the reaction time but are not what is being measured. Therefore, the correct identification of the dependent variable is crucial for understanding the dynamics of the experiment and accurately interpreting the results.