Fact 1: When an electrical circuit is working properly , electrical current runs through that circuit.

Fact 2: Much of the circuit is in fact a comparator made with discrete transistors.

Given the two facts above, answer the question "What has electrical current running through it when working properly?" with the following options: 
- a hydraulic system
 - Marathon runners.
 - deoxyribonucleic acid
 - The bending of a ray of light
 - Electrical tape.
 - Discrete transistors.
 - Ocean currents.
 - electromagnetic energy


 

      Discrete transistors.   