In which situation are unbalanced forces acting on an object?

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.
Two people stand on opposite sides of a large tire. Both people push the tire with equal force.
Two people stand on the same side of a large tire. Both people pull the tire with equal force.
Two people stand on opposite sides of a large tire. Both people pull the tire with equal force.

The situation in which unbalanced forces are acting on an object is when two people stand on opposite sides of a large tire and both people pull the tire with equal force.