You are presented with the quiz "Biomass is the total mass of organisms at a step in the what?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "biomass is the total mass of organisms at a trophic level" and "each of the steps in the food chain is a trophic level ". 

So, what's the best answer to the question?


 

   food chain        