Fact 1: Electron transport is the final stage of aerobic respiration.

Fact 2: Aerobic respiration occurs only in the presence of oxygen.

Given the two facts above, answer the question "Electron transport requires which of the following?" with the following options: 
- electron microscope
 - sodium
 - Energy.
 - Oxygen
 - fission
 - warmth
 - flagellum
 - Energy


 

    Oxygen     