This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
[{'content': 'In treatment of Pseudomonas infections, carbencillin is frequently combined with: \nSelect and explain. \nA. Penicillin, B. Gentamycin, C. Ciprofloxacin, D. Amoxycillin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Gentamycin', 'role': 'assistant'}]