Biology

The correct answer is D.the type of paper airplane.

In this experiment, the independent variable is the factor that the experimenter is changing or manipulating to observe its effect. In this case, the type of paper airplane is being altered to see how it affects the distance flown.

Here’s why the other options are not correct:

A.The paper used: This could be a control variable if different types of paper are used to make different airplanes. It might be kept constant to ensure that the type of paper airplane is the m...