I believe the answer would be d
Virus: an infective agent that typically consists of a nucleic acid molecule in a protein coat, is too small to be seen by light microscopy, and is able to multiply only within the living cells of a host.
Bacteria: a member of a large group of unicellular microorganisms which have cell walls but lack organelles and an organized nucleus, including some which can cause disease.
Fungi/fungus: any of a group of spore-producing organisms feeding on organic matter, including molds, yeast, mushrooms, and toadstools.
Protozoa: a phylum or group of phyla that comprises the single-celled microscopic animals, which include amoebas, flagellates, ciliates, sporozoans, and many other forms. They are now usually treated as a number of phyla belonging to the kingdom Protista.
Awnser : C Lacks genetic variation
Explanation : The major disadvantages of asexual reproduction are: Lack of diversity. Since the offsprings are genetically identical to the parent they are more susceptible to the same diseases and nutrient deficiencies as the parent. All the negative mutations persist for generations.
it can be further divided into epoch
I believe it would be B. More than a year (Since it is a slow change, and that is the longest amount of time). Hopefully this helps