Unbalanced forces are present when the net force acting on an object is not zero, meaning the object will accelerate in the direction of the net force.
Among the given options, the situation that demonstrates unbalanced forces is:
Two people stand on the same side of a large tire. One person pushes the tire and the other pulls the tire with equal force.
In this scenario, the forces exerted in opposite directions do not equal each other (one is pushing and one is pulling), resulting in an unbalanced force that would cause the tire to move in the direction of the net force.