Fact 1: Biomass is the total mass of organisms at a trophic level.

Fact 2: Each of the steps in the food chain is a trophic level .

Given the two facts above, answer the question "Biomass is the total mass of organisms at a step in the what?" with the following options: 
- Energy
 - Plants growth
 - food chain
 - agriculture
 - Animal survival
 - Energy.
 - energy usage
 - kinetic energy


 

   food chain      