Answer the following question given this paragraph: 

Ecological pyramids can demonstrate the decrease in energy, biomass or numbers within an ecosystem. Energy pyramids are discussed at http://www. youtube. com/watch?v=8T2nEMzk6_E (1:44).


Q: What can demonstrate the decrease in energy, biomass or numbers within an ecosystem?

 Choices:

- biomes

- spontaneous mutation

- food chains

- ecological pyramids

A:
ecological pyramids
