Which of the following common habit of patients may cause microbes to re-populate and re-establish an infection?

A. The patient uses OTC drugs prophylactically: OTC (over-the-counter) medications used appropriately shouldn't directly cause microbial repopulation. B. The patient stops taking the drug when he or she begins to feel better: This is the most concerning habit. Stopping antibiotics early allows susceptible microbes to survive and multiply, potentially leading to a recurrent infection. C. The patient switches to multiple drug therapy from single drug therapy: This might be done under a doctor's supervision for complex infections, and wouldn't necessarily promote repopulation. D. The patient increases the drug dosage when he or she perceives that the therapeutic effect is slowing down: Increasing the dosage without consulting a doctor is not recommended, but it wouldn't necessarily cause repopulation if the original dose was effective.