Which term describes a relationship where the organisms are in opposition to each other, actively trying to eliminate one another?

The correct term that describes a relationship between organisms where they are in opposition to each other and actively trying to eliminate one another is antagonism. This type of interaction is characterized by one organism harming or inhibiting the growth of another, often through direct competition for resources or predation. It reflects a conflict scenario where both parties are adversely affected, which may lead to one organism dominating or eliminating the other from the environment.

In contrast, parasitism, mutualism, and commensalism describe different types of relationships. Parasitism involves one organism benefiting at the expense of another, but it does not necessarily imply that the two are trying to eliminate each other. Mutualism refers to a symbiotic relationship where both organisms benefit, and commensalism describes a relationship where one organism benefits while the other is neither helped nor harmed. Understanding these definitions helps clarify why antagonism is the most appropriate term in this context.