Effort force applied to a wheel is when it is transferred to the axle because the axle travels a distance than the wheel.

Effort force applied to a wheel is multiplied when it is transferred to the axle because the axle travels a shorter distance than wheel.

Because wheel and axle can serve as force multiplier, If a wheel attached to the axle then the effort is used to rotate the wheel. And the rotational force is much greater than the force applied to the wheel. The wheel greatly reduces the frictional force when the wheel is moved on the surface of the road.  

i think it would be 5