Q.Select the statement which explains best parasitism.

Parasitism, scored (+, --), is a harmful interaction in which one species, the parasite, benefits at the expense of its host, drawing shelter, food and protection from it while the host is harmed; parasites typically evolve specific adaptations to exploit their host. Parasites are classed by origin (viral, microbial, phytoparasites on plants, zooparasites such as flatworms/nematodes/arthropods on animals) and by location on the host — ectoparasites live on the host's surface (head lice, leeches), endoparasites live within the host's body, often in the alimentary tract, body cavities, organs or blood (Ascaris, tapeworms) — and by d …