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
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) ? 
Select and explain. 
A. Plankton, B. Clams, C. Fish, D. Fish– eating birds
D: Fish– eating birds
Answer: D: Fish– eating birds 
Explanation: None