Final answer:
The relationship described between a botfly and a cow is an example of a parasitic relationship, where the botfly larvae benefit at the expense of the cow, which is harmed.
Step-by-step explanation:
The relationship between a botfly and a cow where the botfly lays eggs under the skin of the cow, and the larvae feed on the cow's blood, is an example of a parasitic relationship. This form of interaction, known as parasitism, is characterized by one organism, the parasite, benefiting at the expense of the other, the host, which is harmed. The botfly larvae benefit by having a source of nourishment and a place to grow, while the cow experiences harm due to the presence of the larvae under its skin.