Fact 1: Producing thrust causes something to move.

Fact 2: An engine is needed to provide the thrust for forward motion.

Given the two facts above, answer the question "causing something to move can need what?" with the following options: 
- heat energy
 - a disc
 - a meal
 - energy
 - an engine
 - voltage
 - a stick
 - arteries


 

     an engine    