Fact 1: Completing a circuit causes electricity to flow through that circuit.

Fact 2: When electric current is flowing, power is produced.

Given the two facts above, answer the question "Power is produced when what happens?" with the following options: 
- circuit is opened
 - circuit is broken
 - heating liquids
 - forest is destroyed
 - circuit is burned out
 - circuit is completed
 - heat energy
 - chemical reaction


 

      circuit is completed   