IF a bacteria were susceptible to both penicillin and Erythromycin, then it would not be appropriate to treat the patients with both antibiotics at the same time because_______________?

A. Penicillin is inactivated by erythromycin
B. Erythromycin exerts its effects extracellularly
C. Erythromycin enhances the B-lactamases activity
D. Penicillin is only effective against growing cells