This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteria, Subject name: Microbiology
A 12-year-old boy, after a camping trip near a wooded area in Northern California, is taken to the emergency room after complaining of a headache. He has an erythema migrans rash around what appears to be a tick bite. Which of the following is the antibiotic of choice for treating this patient? 
Select and explain. 
A. Ampicillin, B. Ceftriaxone, C. Erythromycin, D. Penicillin
B: Ceftriaxone
Answer: B: Ceftriaxone 
Explanation: Campylobacter difficile causes toxin-mediated pseudomembranous enterocolitis as well as antibiotic-associated diarrhea. Pseudomembranous enterocolitis is normally seen during or after administration of antibiotics. One of the few agents effective against C. difficile is vancomycin. Alternatively, bacitracin can be used.