Final answer:
Symbiosis is best described as a mutualistic interaction between two different species where both benefit, although it can also include other types of interactions.
Step-by-step explanation:
The term symbiosis best describes a close and long-term interaction between different species. When looking at the options provided, the most accurate description of symbiosis would be a mutualistic interaction between two different species where both species benefit from the interaction. This is because symbiosis encompasses various types of interactions, including mutualism (where both organisms benefit), commensalism (where one organism benefits and the other is unaffected), and parasitism (where one organism benefits at the expense of the other).