Your Friend Joe Recently Visited the Doctor for Steroid Injections

Your friend Joe recently visited the doctor for steroid injections into his knee to reduce swelling due to previous knee injury.Within a couple of days,he had an infection caused by Pseudomonas,a very pathogenic and drug resistant bacterium.Luckily,Joe went to the doctor immediately and received antibiotics.The doctor tells him that problem has occurred to many other people across the U.S.Predict the most likely cause of this situation:

A) The staff giving the steroid injections did not use proper aseptic technique.
B) The steroid was contaminated at the production plant,so all batches of that drug made at that plant were contaminated with the bacterium.
C) The bacterium is normally on the skin of people,so can easily access the patient's blood during the needle stick.
D) The needles were re-used and already contaminated before being used on the patients.