Question

which statement best describes the variables in a controlled experiment?
the independent variable is changed to see its effect on the dependent variable while all other conditions are unchanged.
the dependent variable is changed to see its effect on the independent variable while all other conditions are unchanged.
the independent variable is allowed to change, and the dependent variable is held constant to see what other conditions show a relationship.
the dependent variable is allowed to change, and the independent variable is held constant to see what other conditions show a relationship.

Explanation:

In a controlled experiment, the independent variable is manipulated, the dependent variable is observed for effects, and other conditions are kept unchanged.

Answer:

The independent variable is changed to see its effect on the dependent variable while all other conditions are unchanged.