Question

what is biomass?
biomass is the total mass of a particular organism or group of organisms in a given ecosystem
biomass refers to the total number of a organisms in a given ecosystem
rewatch

Explanation:

Biomass is defined by the total mass of organisms (not their count) in an ecosystem. The first option aligns with this definition, while the second confuses mass with number of organisms.

Answer:

Biomass is the total mass of a particular organism or group of organisms in a given ecosystem