Over the Past Several Decades, Natural Selection Has Caused Populations

Over the past several decades, natural selection has caused populations of Staphylococcus aureus an infectious wound bacterium) to evolve resistance to most antibiotics. If antibiotic use were stopped, what would you predict would happen to these S. aureus populations?

A) The frequency of resistant forms will definitely increase in these populations.
B) The frequency of nonresistant forms will increase in these populations.
C) They will go extinct without the antibiotic.
D) The populations will begin colonizing new environments.