Question

read the passage about dr. john snow. in 1849, doctor john snow began to question the long - held beliefs that disease was caused by \bad air.\ when a cholera epidemic broke out in london, he interviewed residents of the hardest - hit areas. he mapped cases of the disease and determined that they were centered around a particular water pump. to test his theory that contaminated water was to blame, he convinced local leaders to disable the pump by removing the pumps handle. the outbreak came to an end. what was dr. snows hypothesis? cholera was caused by \bad air.\ cases were centered around a water pump. contaminated water caused cholera. leaders should disable the water pump.

Explanation:

Dr. John Snow questioned the "bad - air" theory. He mapped cholera cases and found they centered around a water pump. His hypothesis was that contaminated water caused cholera. Disabling the pump ended the outbreak, supporting his idea.

Answer:

Contaminated water caused cholera.