Final answer:
Helminths and Rickettsiae are not considered microorganisms because they are larger than typical microorganisms and can be seen without a microscope.
Step-by-step explanation:
The microorganisms that are not considered are C.Helminths and D.Rickettsiae. Helminths are multicellular parasitic worms while Rickettsiae belong to a group of bacteria. Both are not categorized as microorganisms because they are larger than typical microorganisms that can only be seen under a microscope.