Over several years, bacteria were isolated from members of a human population and tested for antibiotic resistance. The percent of bacterial isolates that were found to be antibiotic resistant is presented in the graph above for each year of the study. Which of the following conclusions is best supported by the information presented in the graph?
A.
The greatest increase in antibiotic resistance occurred from the first year to the third year of the study.
B.
Gene flow in the population occurred at the same rate for the entire duration of the eight-year study.
C.
Because evolution in bacterial populations occurs over millions of years, the results are due to random variation.
D.
Natural selection over multiple generations is favoring antibiotic resistance in the population of bacteria.