In the context of your experiment testing the effectiveness of different types of paper airplanes, the independent variable would be:
A. The type of folds made
The independent variable is the factor that you change or manipulate in an experiment to observe how it affects the dependent variable, which in this case is likely the distance of each airplane's flight (option C). Options B and D (the paper used and the color of the paper) could also affect the performance but are not the primary focus based on your description.