What type of symbiotic relationship benefits one organism while harming another?

The correct answer is parasitism, which is a type of symbiotic relationship in which one organism, the parasite, benefits at the expense of another organism, the host. In a parasitic relationship, the parasite derives nourishment or other benefits from the host, which often leads to some degree of harm or damage to the host organism. This can involve various forms of exploitation, such as feeding on the host's nutrients or tissues, which can result in disease or decreased vitality for the host.

In contrast, commensalism describes a relationship where one species benefits while the other is neither helped nor harmed. Mutualism involves both organisms benefiting from the relationship. Symbiosis is a broader term that encompasses any close interaction between two different species, including mutualism, commensalism, and parasitism. Therefore, in the context of the question, parasitism specifically highlights the interaction that results in one party benefitting while the other suffers.