Step 1: Definition of population.
In ecology, a population refers to organisms of the same species living in a specific area at a particular time.
Step 2: Key features.
All individuals belong to the same species and share resources and habitat.
Step 3: Elimination of incorrect options.
Population does not include all organisms of the planet or only plants or animals.
Step 4: Conclusion.
Thus, a population is a group of individuals belonging to the same species.