Pasteur Worked on Rabies and Cholera Vaccine During the Emergence

Multiple Choice

Pasteur worked on rabies and cholera vaccine during the emergence of immunology.While culturing a chicken cholera he noted that an old culture was weakened and useful as a vaccine as it:

A) caused disease
B) caused severe cholera symptoms and prevented further infection
C) allowed for the cholera to spread from person to person
D) did not cause disease symptoms and immunized against chicken cholera