What is the definition of a host in the context of parasitology?

In the context of parasitology, a host is defined as a living organism that provides nutrients to another organism, usually a parasite. This relationship is fundamental in understanding how parasites survive and reproduce. The host serves as a habitat for the parasite, supplying it with resources such as food and shelter necessary for its life cycle.

The other options do not accurately capture the essence of what a host is in parasitology. While options involving mosquito larvae or pesticides touch on related ecological concepts, they don't define a host within the specific framework of parasitism. The parasitic relationship is characterized not just by the presence of organisms, but particularly by the interaction where one organism benefits at the expense of another, which aligns directly with the definition of a host.