Final answer:
The correct option is 3. In determining if a relationship is symbiotic, the key factor is the degree of proximity between the two interacting parties. Symbiosis includes mutualism, commensalism, and parasitism, but the benefit gained isn't necessarily equal for both parties. An example is the mutualistic relationship between clownfish and sea anemones.
Step-by-step explanation:
Symbiosis and Ecological Relationships
The most important criterion in determining whether an ecological relationship is a symbiosis is the degree of proximity between the two parties. The essence of symbiotic relationships is that they are close, long-term interactions between individuals of different species. There needs to be some level of physical closeness which constitutes the association characteristic of symbioses.
In a mutualistic relationship, which is a type of symbiotic relationship, both parties benefit but not necessarily to the same degree. Sometimes, one organism may receive a smaller benefit, which is still considered mutualism. An example of such an interaction is the relationship between clownfish and sea anemones. Clownfish are protected from predators by the stinging tentacles of the sea anemone, while the anemone might receive fewer benefits such as the removal of parasites by the clownfish.
The benefit to both parties is not a requirement for a relationship to be termed symbiotic, as commensalism involves one party benefiting while the other remains unaffected, and parasitism involves one party being harmed while the other benefits. Additionally, whether the parties are from the same kingdom or the number of parties in the interaction does not define symbiosis. The protective mucus of clownfish, which keeps them from being stung by the anemone's tentacles, could be developed through adaptation or acquired from the anemone itself—this is one small facet of their symbiotic relationship.
The correct option to determine if a relationship is symbiotic is 3) The degree of proximity between the two parties.