A patient develops severe watery diarrhea after consuming contaminated seafood. Stool culture grows a Gram-negative, comma-shaped bacterium that produces a toxin causing irreversible activation of adenylyl cyclase. Which organism is the most likely culprit?

✓ Correct Answer: Option C

Vibrio cholerae produces cholera toxin, which ADP-ribosylates the Gs alpha subunit, leading to irreversible activation of adenylyl cyclase and increased cAMP. This causes massive secretion of water and electrolytes into the intestinal lumen.