Context: Barbara is sitting on a roller coaster cart as it reaches the bottom of a big loop. Earth's gravity is pulling down on Barbara with a force of 600N. The seat of the cart is pushing up on Barbara with a force of 1,200N.
Assume all other forces on Barbara are balanced. Which statement describes the forces on Barbara?
A. The forces are balanced, so there is no net force on Barbara.
B. The forces are unbalanced, so there is a net force on Barbara.
Select the correct answer from the provided options and reply with the letter associated with it.

B