Physically close association between interacting species (mutualism)

• A. Symbiosis
• B. Community
• C. Population Distribution
• D. Resource Partitioning

Answer: (A)

Symbiosis is the term for a close, long-term interaction between two different species. When the interaction benefits both partners, it's a form of symbiosis known as mutualism, which is what the prompt alludes to by describing a physically close association. In symbiotic relationships, the partners often live in direct contact or in very near association and depend on each other for resources or survival—for example, fungi and algae in lichens, plant roots with mycorrhizal fungi, or pollinators and flowering plants. The other terms describe broader or different ecological ideas: a community is all the species in an area, population distribution refers to how individuals of a species are spaced, and resource partitioning explains how similar species divide resources to reduce competition. Therefore, the best fit for a physically close association between interacting species, with mutual benefits, is symbiosis.