The independent variable is a variable that can be stood alone. So therefore, the independent variable would be how long it takes to parachute.
The net force is the vector sum of all the forces that act upon an object. That is to say, the net force is the sum of all the forces,
I think the correct answer from the choices listed above is option A. The process that is being described above is called succession. Ecological succession is the process of change in species structure in a community as time goes by. Hope this answers the question.
