This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Mycobacterial Infections, Subject name: Dental
[{'content': 'Patient with leprosy, smear sample taken show 10- 100 bacilli in one field. Bacterial index is: \nSelect and explain. \nA. 1+, B. 2+, C. 3+, D. 4+', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Bacterial index is calculated by counting the number of bacilli in 100 fields under oil immersion Grade Number of bacilli 1+ 1 to 10 bacilli per 100 fields 2+ 1 to 10 bacilli per 10 fields 3+ 1 to 10 bacilli per field 4+ 10 to 100 bacilli per field 5+ 100 to 1000 bacilli per field 6+ Multiple clumps of bacilli present', 'role': 'assistant'}]