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': 'In the bioaccumulation of DDT in the aquatic food chain of Plakton → Clams → Fish– eating birds, which group of organisms exhibits highest concentration of DDT (in their bodies) ? \nSelect and explain. \nA. Plankton, B. Clams, C. Fish, D. Fish– eating birds', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]