Final answer:
In commensalism, one species benefits while the other is neither harmed nor benefited. An example is the relationship between barnacles and whales.
Step-by-step explanation:
In commensalism, one species benefits while the other is neither harmed nor benefited. An example is the relationship between barnacles and whales. Barnacles attach themselves to the whale's skin and benefit by gaining a habitat and access to food particles, while the whale is not harmed or helped. Therefore, the correct answer is A: commensalism.
Learn more about Symbiotic relationships