You are presented with the question "What on the pedals of a bike cause that bike to move?" and the following answer choices: 
- force
 - heat
 - nothing
 - a lack of energy
 - zero energy
 - muscles
 - speed
 - motion

Now knowing that pushing on the pedals of a bike cause that bike to move and force is a push or a pull, choose the best answer.


 

 force        