Darwin's finches are a group of seed-eating bird species found on the Galápagos Islands. Nest flies are a type of insect that has become a threat to the finches. The
diagram shows the life cycle of the nest fly.

The young birds are hosts for the larvae.

Explanation:

A host is an organism that harbours the invertebrate or microorganism and experiences disease. The disease that the larvae are causing is threatening the population of birds.

just finished the test, the answer is d, greg is the least cost-effective because he charges the most for the project