This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
Most common drug causing peudomembranous enterocolitis is 
Select and explain. 
A. Cephalosporin, B. Doxycycline, C. Ampicillin, D. Amoxicillin
C: Ampicillin
Answer: C: Ampicillin 
Explanation: C.difficile causes acute colitis with bloody and watery diarrhea and pseudomembranous colitis. C.difficle is the most common cause of healthcare-associated diarrhea in many developed countries following the use of broad-spectrum antibiotics like clindamycin, ampicillin, or fluoroquinolones to which the organism is resistant. Ref: Textbook of microbiology; Ananthanarayan and paniker's; 10th Edition; Pg: 270