Answer:
Option 2, Salmon
Explanation:
Large fishes such as shark and sword fish have higher level of mercury. This fact can be explained by the concept of bio magnification in which an individual lying at a higher trophic level in a food chain gets accumulated toxin and hence possess the highest amount of toxin in a given food chain. Small fish such as salmon will have the lowest amount of mercury as they lie at the lower level of a food chain and hence possess a small amount of toxin
