In an experiment, the weight that mice gain is the dependent variable and the temperature of the environment is the independent variable. What must be held constant to obtain valid experimental results?

To test whether environmental temperature affects weight gain, other factors that could affect the mice’s weight should be kept the same. The type and amount of food should therefore be held constant, so differences in weight gain can be linked to temperature rather than diet. The correct choice is “the type of food given to the mice.”

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