A microbiologist inoculates Staphylococcus aureus into a culture medium. Following incubation, both Staphylococcus aureus and Staphylococcus epidermidis are determined to be growing in this culture. What is the most likely explanation?
A) The culture was contaminated. B) The culture medium was selective. C) The incubation temperature was incorrect. D) The culture medium was differential. E) The microbiologist used too much inoculum.