Dr. John Snow is renowned for identifying:

Dr. John Snow is renowned for identifying:

• A. Discovered the germ theory of disease
• B. Led the vaccination campaign for smallpox
• C. Developed Koch's postulates
• D. Contributed to identifying the Broad Street Pump as linked to cholera outbreaks

Answer: (D)

The key idea tested is how disease investigations identify a source of transmission and use that to guide action. John Snow’s famous contribution was tracing a cholera outbreak to a specific water source—the Broad Street pump in London. By mapping cases, comparing different water supplies, and observing that removing the pump handle led to a drop in new cases, he showed that contaminated water could spread cholera. This work is a landmark in epidemiology because it demonstrates how data, observation, and a targeted intervention can control an outbreak, even before germ theory was fully established. He did not discover the germ theory (that work belongs to others like Pasteur), did not develop Koch's postulates, and did not lead a smallpox vaccination campaign (that was Jenner). So identifying the Broad Street pump as linked to cholera outbreaks is the best answer.

The key idea tested is how disease investigations identify a source of transmission and use that to guide action. John Snow’s famous contribution was tracing a cholera outbreak to a specific water source—the Broad Street pump in London. By mapping cases, comparing different water supplies, and observing that removing the pump handle led to a drop in new cases, he showed that contaminated water could spread cholera. This work is a landmark in epidemiology because it demonstrates how data, observation, and a targeted intervention can control an outbreak, even before germ theory was fully established. He did not discover the germ theory (that work belongs to others like Pasteur), did not develop Koch's postulates, and did not lead a smallpox vaccination campaign (that was Jenner). So identifying the Broad Street pump as linked to cholera outbreaks is the best answer.