Cholera: Vibrio cholerae via contaminated water

Steps:

• Recall cholera's causative agent is the bacterium Vibrio cholerae, matching option 1.
• Identify primary transmission as fecal-oral route through contaminated water or food, aligning with method W.
• Eliminate viral or parasitic agents (options 2 and 3) as they do not cause cholera.
• Rule out airborne (X) or vector-borne (Y) transmission, as cholera spreads via poor sanitation.

Why A is correct:

• Vibrio cholerae (1) produces cholera toxin leading to severe diarrhea; waterborne spread (W) is defined by WHO as the main route in epidemics.

Why the others are wrong:

• B: Shares correct pathogen (1) but wrong transmission (X, airborne—not cholera's method).
• C: Wrong pathogen (2, likely viral) and transmission (X, airborne).
• D: Wrong pathogen (3, likely parasitic) and transmission (Y, vector-borne).

Final answer: A