A female client develops a vaginal superinfection during antibiotic therapy for pneumonia and asks the nurse "How did I get another infection while taking an antibiotic?" Which is the best response by the nurse?

"The bacteria that caused your pneumonia has become resistant to the drugs."

"Normal flora is also eliminated by antibiotics and allows other organisms to grow."

“The infection has spread from your lungs to a new site."

“This is an allergic reaction to the antibiotics."