Which refers to the sum of all the forces that act upon an object? A. net force

B. absolute force

C. balanced force

D. positive force

Net force

Explanation:

Net force is the vector sum of forces acting on a particle or body. The net force is a single force that replaces the effect of the original forces on the particle's motion. It gives the particle the same acceleration as all those actual forces together as described by the Newton's second law of motion.

"a.) well–developed vascular system."