The highest DDT concentration in aquatic food chain shall occur in

Correct option is D. Seagull
DDT (dichloro, diphenyl, trichloroethane) is long chain stable and fat soluble hydrocarbon which is readily accumulated in fat tissues of organisms. Slow metabolism and excretion of DDT cause its accumulation in fat tissues of organisms (biomagnification), particularly affecting the top consumers (carnivores) causing the decrease in their population size. Phytoplankton are primary producers while Seagull is top consumers among the given option that feed on dead or live fishes and will exhibit highest DDT concentration.Therefore, the correct answer is option D.