Final answer:
The net force on the ball is found by subtracting the force of friction from the applied force, resulting in 16.3 N.
Step-by-step explanation:
The net force on a ball rolling across a field can be calculated by subtracting the force of friction from the applied force. Since the ball is pushed with an applied force of 20 N and there is a frictional force of 3.7 N opposing the motion, the net force is the result of 20 N - 3.7 N. Therefore, the net force acting on the ball is 16.3 N, which corresponds to option a. 16.3 N.