Regarding microbes and their presence, which of the following statements are accurate?
a. Microbes are major components of biological systems and are present only in soil and water, but not in air.
b. Microbes include protozoa, bacteria, fungi, viruses, viroids, and proteinaceous infectious agents called prions.
c. Some microbes can exist in extreme conditions like geysers at 100 degrees C or highly acidic environments.
d. Microbes like bacteria and fungi can be grown on nutritive media to form colonies visible to the naked eye.
e. All microbes are harmful to human beings, causing a large number of diseases in humans, animals, and plants.
