While testing the falling time of parachutes of different sizes, which is the independent variable?

Correct answer: Size of parachute

The governing concept is experimental variable classification. The independent variable is the factor deliberately changed to investigate its effect. Here the investigator compares parachutes of different sizes, so parachute size is the independent variable and option A is correct. Falling time is the measured response, making it the dependent variable. Drop height and suspended mass should normally be kept constant so that they do not provide alternative explanations for differences in falling time; they are controlled variables. If either were changed as well, the test would no longer isolate the effect of parachute size. A fair comparison therefore changes size alone and records repeated falling times.