Final answer:
Symbiosis refers to a close relationship between two organisms of different species, with at least one benefiting. Mutualism, commensalism, and parasitism are types of symbiotic relationships. Mutualism benefits both species, commensalism benefits one while not affecting the other, and parasitism benefits one at the expense of the other.
a) Mutualism
Step-by-step explanation:
Symbiosis is a close relationship between two organisms of different species in which at least one of the organisms benefits. There are three basic types of symbiosis: mutualism, commensalism, and parasitism. In mutualism, both species benefit. For example, bees and flowers have a mutualistic relationship because bees collect nectar from flowers while transferring pollen, which helps the flowers reproduce.
In commensalism, one species benefits while the other is not affected. An example is the relationship between barnacles and whales. Barnacles attach themselves to a whale, which provides protection and increased exposure to food for the barnacles, while the whale is not bothered by their presence.
In parasitism, the parasitic species benefits while the host species is harmed. A common example is the relationship between ticks and dogs. Ticks feed on the blood of dogs, which harms the host by causing irritation and potential diseases.