Question

in an experiment, a scientist wants to see if copper affects a solution. he changes the amount of copper he adds to the solution he is analyzing. thus, the amount of copper is the: dependent variable constant independent variable

Explanation:

In an experiment, the independent variable is the one that the experimenter manipulates (in this case, the amount of copper added). The dependent variable depends on the independent variable (the effect on the solution), and a constant is unchanged. Since the scientist changes the amount of copper, it's the independent variable.

Answer:

independent variable (the option with "independent variable" text, assuming the options are as shown: the third option if we consider the radio buttons, but based on the text, the correct choice is the one labeled "independent variable")