Volpe's Understanding Evolution 7th Edition by Peter Rosenbaum

Exercise 13

Bacterial resistance to antibiotic is a prime example of rapid natural selection. What factor was most important in the rapid evolution of bacterial resistance to antibiotics?
A) The nature of the bacterial immune system
B) The fact that bacteria already had genetic resistant genes in its gene pool due to previous exposure to other substances that mimic the effects of antibiotics.
C) The short generation time of bacteria.
D) The ability of bacteria to mutate new genes in response to antibiotics.
E) The fact that humans had been exposed to disease for millions of years.