Final answer:
The correct option is d. Exotoxins have a local effect rather than a systemic effect. They are protein molecules produced by various living pathogenic bacteria, mainly gram-positive bacteria. Examples include diphtheria toxin, cholera toxin, botulinum toxin, and tetanus toxin.
Step-by-step explanation:
Exotoxins have a local effect rather than a systemic effect. They are protein molecules produced by various living pathogenic bacteria, mainly gram-positive bacteria. Exotoxins differ from endotoxins in their specificity and mechanism of action, targeting specific receptors on specific cells and damaging those cells through unique molecular mechanisms.
Examples of exotoxins include diphtheria toxin, cholera toxin, botulinum toxin, and tetanus toxin. These exotoxins belong to the A-B toxin class, where the B component attaches to specific cell surface receptors and the A component enters the cell cytoplasm to interfere with the specific internal cellular function it targets.