Which of the following may be considered microorganisms?

• A. Mushrooms
• B. Oak trees
• C. Bacteria
• D. Viruses

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the definition of microorganisms. Microorganisms are tiny living organisms that are usually too small to be seen with the naked eye and include bacteria, viruses, fungi (like yeasts and molds), and some algae and protozoa.
2. Step 2: Analyze each option given in the problem. Mushrooms are fungi but are macroscopic (visible to the naked eye), so they are not considered microorganisms in their mature form.
3. Step 3: Oak trees are large plants and clearly macroscopic, so they are not microorganisms.
4. Step 4: Bacteria are single-celled organisms that are microscopic, so they fit the definition of microorganisms.
5. Step 5: Viruses are microscopic infectious agents that can only replicate inside host cells, and despite not being cells themselves, they are considered microorganisms due to their size and biological impact.