Hundreds of years ago, which of the following did doctors believe was a major cause of disease? A. Bacteria
B. Leeches
C. All of these
D. Unbalanced humors

A. Bacteria.

Explanation:

That was why penicillin was manufactured, because doctors believed bacteria was a major cause of diseases.

Hope it helps.

from the original order (top to bottom) the new order will go

1 (founder)

4 (hawk)

2 (mutate)

3 (next generation)