As She Is Preparing to Leave Your Office, the Patient

As she is preparing to leave your office, the patient mentions that her brother had pneumonia a couple of years ago and that penicillin had not helped him. You ask her if she remembers the name of the organism causing her brother's illness and she tells you it was Mycoplasma something or other, that she can't quite remember. You tell her that the reason penicillin did not help her brother is that 

A) you know her brother did not take the full course of antibiotics, so some of the Mycoplasma cells survived.
B) Mycoplasma species are Gram-negative, and penicillin cannot penetrate the LPS layer of these cells, so the cells survive.
C) Mycoplasma species are acid-fast bacteria, so they have mycolic acids in the cell wall that penicillin does not destroy.
D) Mycoplasma species do not have a peptidoglycan cell wall and are thus not impacted by penicillin.
E) Mycoplasmas are viruses and antibiotics do not work for viral infections.