This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Chemotherapy, Subject name: Pharmacology
A post operative patient developed septicemia and was empirically staed on combination chromotherapy by a new resident doctor. However when the patient did not respond even after 10 days of antibioti treatment.it was found that resident doctor had staed the combination of antibiotics which was mutually antagonistic in action.which of the following is the most likely combination that was given 
Select and explain. 
A. Vancomycin and Amikacin, B. Cephalexin and gentamicin, C. Ampicillin and chloramphenicol, D. Ciprofloxacin and piperacillin
C: Ampicillin and chloramphenicol
Answer: C: Ampicillin and chloramphenicol 
Explanation: Combination of a bactericidal and a bacteriostatic drug is usually antagonist in nature. This is because cidal drugs are usually acting on a fast multiplying organisms whereas static drugs decrease this multiplication