This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Anatomy
[{'content': 'Metrinidazole is least likely to be effective in the treatment of \nSelect and explain. \nA. Hepatic amoebiasis, B. Infection caused by bacteroides fragilis, C. Pseudomembranous colitis, D. Pneumocystosis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ref-KDT 6/e p686 Metranidazole is not effective against pneumocyst infection. The DOC for this condition is cotrimoxazole', 'role': 'assistant'}]