You are presented with the question "What has electrical current running through it when working properly?" and the following answer choices: 
- a hydraulic system
 - Marathon runners.
 - deoxyribonucleic acid
 - The bending of a ray of light
 - Electrical tape.
 - Discrete transistors.
 - Ocean currents.
 - electromagnetic energy

Now knowing that when an electrical circuit is working properly , electrical current runs through that circuit and much of the circuit is in fact a comparator made with discrete transistors, choose the best answer.


 

      Discrete transistors.   