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: Social & Preventive Medicine
[{'content': 'Which insect amongst the following has not developed resistance to DDT? \nSelect and explain. \nA. Musca Domestica, B. Phlebotomus species, C. Xenopsylla species, D. Anopheles species', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Phlebotomus species or sandflies have not yet shown resistance to DDT. Ref: Preventive and Social Medicine, by K.Park, 19th edition, Page 627, 629, 630 and 633.', 'role': 'assistant'}]