You are presented with the question "What do ecosystems in nature need an influx of to remain feasible?" and the following answer choices: 
- Continuous nuclear energy.
 - Natural lipids and proteins.
 - Energy.
 - rain
 - water
 - Energy
 - oxygen
 - Renewable Sunny Delight.

Now knowing that energy enters ecosystems in the form of sunlight or chemical compounds and sunlight is the source of light in nature, choose the best answer.


 

   Energy.      