Answer:
The answer is D. Miasma theory. Proponents of the miasma theory believed that diseases such as cholera were caused by "bad air" or the inhalation of miasma, which was believed to be a type of poisonous mist or vapor that originated from decomposing organic matter. John Snow's theory that cholera was waterborne and spread through contaminated water was in opposition to this prevalent theory and was met with resistance from many in the medical community who adhered to the miasma theory. Snow's waterborne theory of cholera has since been confirmed, and he is widely credited as one of the founders of modern epidemiology.
Step-by-step explanation: