Answer:
B. All of the fish, bacteria, and mammals that live in a lake
Explanation:
In terms of biology an individual make population, population makes a species and interaction between different species makes community. Interaction of living and non-living things make an ecosystem.
Community involves interaction between all the living organisms present in a given environment. Hence, interaction between fish, bacteria, and mammals that live in a lake is a community.
Hence, the correct answer is "B. All of the fish, bacteria, and mammals that live in a lake".
