All of the following organisms produce exotoxins except:

• A. Fungi
• B. Protozoa
• C. Bacteria
• D. Viruses

Answer: (D)

Verified step by step guidance

1. Step 1: Understand what exotoxins are. Exotoxins are toxic proteins secreted by certain living bacteria into their surrounding environment. They are typically heat-labile and highly potent.
2. Step 2: Identify which groups of organisms are known to produce exotoxins. Bacteria are well-known producers of exotoxins, which contribute to their pathogenicity.
3. Step 3: Consider fungi and protozoa. While fungi and protozoa can produce various harmful substances, they generally do not produce exotoxins in the same way bacteria do.
4. Step 4: Analyze viruses. Viruses do not produce exotoxins because they rely on host cells to replicate and do not secrete proteins independently; their pathogenicity is due to other mechanisms.
5. Step 5: Conclude that among the options, viruses are the organisms that do not produce exotoxins, making them the correct answer to the question.