Answer:
Innoculate cattle against infection.
Step-by-step explanation:
Biologists work on both biotic and abiotic factors, such as cows and viruses that make the infection. A isn't right because it focuses on a material and not a biotic factor like the bees. C isn't right because that is what a paleontologist does, study fossils and other items that are of ancient age. D isn't right because that is what a toxicologist does, they test the harmfulness of certain materials on test objects.