Options are:
1). force.
2). heat.
3). nothing.
4). a lack of energy.
5). zero energy.
6). muscles.
7). speed.
8). motion.

Fact 1: Pushing on the pedals of a bike cause that bike to move. Fact 2: Force is a push or a pull. Given the two facts above, what on the pedals of a bike cause that bike to move?
Answer:
1).