Biomass is the total mass of organisms at a trophic level.
Fourty percent of biomass is carbon.
Fourty percent of the total mass of organisms at a trophic level is carbon.
What is fourty percent of the total mass of organisms at a trophic level?
Options:
  - worms
  - carbon
  - Energy
  - leaves
  - blood
  - fungi
  - Energy.
  - food