Answer:
Contaminated water caused cholera
Step-by-step explanation:
John Snow was a physician who was considered to be one of the founders of modern epidemiology,He discovery in 1854 that cholera is conveyed by water. Dr. Snow was not in agreement with miasma theory that stated that diseases such as cholera were caused by pollution.He believed sewage dumped into the river or near town wells (water pumps) could contaminate the water supply which cause cholera. Snow tested his hypothesized by interviewing households with the sick and dying due to the disease to make marking and pattern of the pandemic on city maps. His finding leads to the conclusion that contaminated water caused cholera not pollution or bad air as believed by some physicians.