Answer:
The correct answer will be option-A
Explanation:
The ecological population is the group of the organism belonging to the same species which live or is found in the particular area and can interbreed.
Since in the given question, the redwood trees live in the same geographical area (forest) which can interbreed shows the population. The other examples represent the community which consists of more than one species.
Thus, option-A is the correct answer.