Symbiosis refers to a close and often long-term interaction between two different biological species. It can take several forms:
- Mutualism: A relationship where both organisms benefit.
- Commensalism: A relationship where one organism benefits and the other is not significantly affected.
- Parasitism: A relationship where one organism benefits at the expense of the other, harming it.
Thus, the correct answer to your question about symbiosis would be that it refers to when members of two or more species live in extremely close contact with each other, which can result in any of these types of relationships.