In an experiment, which variable is deliberately changed by the scientist?

• A. Dependent variable
• B. Independent variable
• C. Control variable
• D. Constant

Answer: (B)

The main idea is about what a scientist changes on purpose to test its effect. The variable that is deliberately changed is the independent variable. You set or alter this factor to see how it influences the outcome, which you measure as the dependent variable. Everything else that could affect the result is kept the same so that any observed change can be linked to the independent variable; those are the control variables. A constant is simply something that doesn’t change, and while constants help keep the experiment fair, they aren’t the variable you manipulate. For example, in a plant growth test, changing the amount of fertilizer is the independent variable, plant height or growth is the dependent variable, and other factors like light, water, and soil are kept constant as control variables.