What is symbiosis?

Symbiosis refers to a close and long-term interaction between two different species, and it is characterized by the fact that at least one of the species involved benefits from the relationship. This definition encompasses various types of interactions, including mutualism (where both species benefit), commensalism (where one species benefits while the other is neither helped nor harmed), and parasitism (where one species benefits at the expense of the other).

Option B effectively captures the essence of symbiosis by highlighting that it involves a close relationship and specifies that at least one species gains an advantage from it. This broader understanding of symbiosis makes it more comprehensive compared to the other options, which either limit the relationship to one that benefits only one species without considering any positive effects on others, or describe relationships that are negative or neutral, which do not fall under the concept of symbiosis.