Answer:
1. organism
2. population
3. community
4. ecosystem
Explanation:
Let's define all these terms.
Community: the level where different populations of living organisms interact with each other
Ecosystem: the level where various communities of organisms interact with their nonliving environment
Organism: a single living thing
Population: a group of one specific organism
Observing these definitions, notice that a population is made up of organisms, a community is made up of populations, and an ecosystem is made up of communities.
Hope this helps!
