Which statement best describes the variables in a controlled experiment?

• A. Both the independent and dependent variables are kept constant.
• B. The dependent variable is manipulated while the independent variable is measured.
• C. All variables are manipulated to observe different outcomes.
• D. The independent variable is manipulated while the dependent variable is measured.

Answer: (D)

Verified step by step guidance

1. In a controlled experiment, the independent variable is the one that the experimenter changes or manipulates to observe its effect.
2. The dependent variable is what the experimenter measures or observes in response to changes in the independent variable.
3. The purpose of manipulating the independent variable is to determine if it causes any change in the dependent variable.
4. All other variables in the experiment should be kept constant to ensure that any observed changes in the dependent variable are due to the manipulation of the independent variable.
5. Thus, the correct description of a controlled experiment is that the independent variable is manipulated while the dependent variable is measured.