Vibrio cholera is a bacterium that causes the diarrheal disease known as cholera. In the 1800s Louis Pasteur noticed that old Vibrio cholera cells did not cause disease in chickens, whereas new
V. cholera cells did cause disease. He also noticed that chickens previously inoculated with old
cells could not be made sick by new V. cholera cells. Based on Pasteur's observations, which of the
following represents a good hypothesis?

''If the old cells inoculated in chicken, it produces resistance in the chicken against new V. cholera cells.''

Explanation:

From the data provided by Louis Pasteur, we make a hypothesis i. e. ''If the old cells inoculated in chicken, it produces resistance in the chicken against new V. cholera cells.'' From these observation we can assume that by allowing old V. cholera cells to chicken, it did not cause any disease but make immunity against the new V. cholera cells which are more effective from old V. cholera cells.