If a waterbody is contaminated with a toxicant it's biomagnification will be more marked in (a) water (b) plankton's (c) small fishes (d) birds

Biomagnification means when the concentration of a substance is increased beyond its optimal concentration. Biomagnification in light of pesticides refers to the moving of pesticides up to the food chain. When a fish have been contaminated water rich in pesticides then these pesticides will accumulate in the tissues and organs of these fishes. The fishes are then eaten up by birds concentration of pesticides will occur up in the food chain. Therefore, option (d) is correct.