Question

ecosystem
population
biosphere
a
b
c
a b c
ecosystem ○ ○ ○
population ○ ○ ○
community ○ ○ ○

Explanation:

1. Population: The smallest, most specific level here, consisting of a single group of the same species, so it matches the innermost square A.
2. Ecosystem: Includes all living organisms (a community) plus their non-living environment, which is a larger scope than population, matching square B.
3. Biosphere: The largest level, encompassing all ecosystems on Earth, matching the outermost square C.

Answer:

Ecosystem: B
Population: A
Biosphere: C