A parasitic association is one in which a species, the parasite, thrives off of another species, that is, the host, affecting it, and at certain occasion resulting in death. The parasite lives on or within the body of the host.
An ectoparasite refers to the parasite, which thrives on or in the skin, but not inside the body. For example, lice, ticks, and fleas are ectoparasites. Hence, the correct answer is option B.
