Your text discusses the evolution of antibiotic- resistant M. tuberculosis bacteria in a patient. Researchers discovered that the strain of M. tuberculosis taken from the dead patient has a point mutation in the rpoB gene that codes for part of the RNA polymerase enzyme. This mutant form of RNA polymerase does not normally function as well as the more common form, but a commonly used antibiotic called rifampin does not affect the mutant rpoB. A researcher places M. tuberculosis isolated from the patient a year before death no rpoB mutation) in cell cultures with M. tuberculosis isolated from the dead patient with rpoB mutation). Half the cell cultures contain just standard nutrients, and the other cell cultures contain rifampin in addition to the standard nutrients. After many cell generations, the researcher finds that
A) almost all M. tuberculosis in the standard nutrient cell cultures carry the rpoB gene mutation, but very few of the M. tuberculosis in the cell cultures with rifampin carry the rpoB mutation. B) a mix of both M. tuberculosis strains thrive in the standard cell cultures, but no living bacteria can be found in the cell cultures that contain rifampin. C) very few M. tuberculosis in any of the cell cultures carry the rpoB gene mutation. D) very few M. tuberculosis in the standard nutrient cell cultures carry the rpoB gene mutation, but almost all of the M. tuberculosis in the cell cultures with rifampin carry the rpoB mutation. E) almost all of the M. tuberculosis in both types of cell cultures carry the rpoB mutation.