A microbiologist inoculates Staphylococcus epidermidis and Escherichia coli into a culture medium. Following incubation, only the E. coli grows in the culture. What is the most likely explanation?
a. The microbiologist used too much inoculum.
b. The culture is contaminated.
c. The incubation temperature was incorrect.
d. The culture medium must be selective.
e. The culture medium must be differential.