What does the professor say about the microbes in a reindeer's digestive system? A. Some of the microbes protect the reindeer against harmful bacteria. B. Many of the microbes are transported into the reindeer's body on lichens that the reindeer eats. C. The proportion of various microbes changes to accommodate changes in the reindeers diet. D. The microbes found in a newborn reindeer's digestive system are very different from those found in an adult reindeer.