Hundreds of years ago, doctors believed that bacteria were a major cause of disease. Thus, the correct option is A.
What is Disease?
The Disease may be defined as a type of disorder that involves physical or mental sickness with respect to external signs and symptoms.
In past times, science, medical department, and technology are not so evolved, so doctors do not have enough evidence to classify various types of diseases.
They similarly categorize most types of disease into the bacterial classification. It can also be estimated by the discovery of penicillin by Alexander Fleming with the help of Staphylococcus bacteria.
Therefore, hundreds of years ago, doctors believed that bacteria were a major cause of disease. Thus, the correct option is A.
To learn more about Bacterial diseases, refer to the link:
https://brainly.com/question/2009215
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