Here's why:
* Population: A group of individuals of the same species living in the same area and capable of interbreeding. Even though it's just one individual, it represents the potential for a larger group of howler monkeys in that area.
Let's look at other terms and why they don't fit:
* Community: All the different populations of organisms living in the same area. This would include the howler monkeys, along with all the other plants and animals in the rainforest.
* Ecosystem: All the living organisms in a particular area (community) and their interactions with the non-living components of the environment (like soil, water, and sunlight).
* Biosphere: The sum of all ecosystems on Earth.
Let me know if you have any other questions!