What does commensalism refer to in terms of microorganism relationships?

Commensalism refers to a type of relationship between two organisms where one organism benefits while the other is neither helped nor harmed. This type of interaction often involves microorganisms that live on or within a host organism without causing any damage or providing any benefit. A common example of commensalism can be found in the human gut, where certain bacteria can reside and thrive without affecting the host's health.

The correct answer reflects the essence of commensalism, emphasizing that the interaction does not disadvantage the host organism. In contrast, other forms of symbiotic relationships, like mutualism, involve benefits for both parties, while parasitism denotes a harmful relationship for one party.