On what street and year did John Snow discover the link between contaminated water and cholera?

• A. Fleet Street, 1860
• B. Soho Street, 1844
• C. Broad Street, 1854
• D. Oxford Street, 1850

Answer: (C)

Tracing outbreaks to a water source through pattern mapping is the key idea here. John Snow showed cholera was linked to contaminated water during the 1854 Soho outbreak by plotting where deaths occurred and linking many of them to the Broad Street pump. When the pump handle was removed, new cholera cases fell, which supported the idea that the water supply, not miasma or bad air, spread the disease. That combination of data and intervention makes Broad Street in 1854 the correct match. Other streets or dates don’t fit the specific investigation Snow carried out in that outbreak.