The correct answer is the concentration of DDT should increase as we go to higher trophic-levels. Explanation: Biomagnification or biological magnification is defined as an increase in the concentration of toxicants at successive trophic levels. DDT (dichlorodiphenyldichloroethane) and mercury are well known for biological magnification. DDT is a pesticide that is non-degradable and so tends to enter organisms. Their concentration increases with each tropical level. DDT concentrations in the water begin at 0.003 ppb (parts per billion). Its concentration rises by biological magnification with each tropical level, reaching up to 25 ppm (parts per million) in fish-eating birds. This is due to the fact that consumers at each subsequent trophic level consume more energy than the previous level. When toxic compounds enter the aquatic food chain, they get accumulated in the organism's body and cannot be excreted and metabolised, so they pass it from one trophic level to the next. Thus, The concentration of DDT should increase as we go to higher trophic levels. Hence option 2 is incorrect.