The one variable that is manipulated by a scientist as a potential cause in an experiment is the _________.

• A. The constant
• B. The control group
• C. The dependent variable
• D. The independent variable

Answer: (D)

In experiments, the factor you deliberately change to see its effect is the independent variable. It’s the potential cause you’re testing. The thing you measure to see what happened is the dependent variable. Constants are the conditions kept the same so they don’t influence the outcome, and the control group provides a baseline for comparison so you can judge whether changes in the independent variable actually made a difference. For example, if you’re investigating how different amounts of fertilizer affect plant growth, the amount of fertilizer is the independent variable, plant height or biomass is the dependent variable, and factors like soil type, light, and watering are kept constant. A plant group that receives no fertilizer acts as the control. So, the variable manipulated by the scientist as the potential cause is the independent variable.