lead arsenic mercury aluminum
I gave my students this multiple choice question: When chemicals in the atmosphere dissolve in water droplets, they precipitate with the water and pollute water reservoirs on Earth. The pollutants enter the food chain when aquatic organisms absorb them. Which of these pollutants eventually contaminates fish after coal is burned?

Only one answer is correct among these 4 choices:
- lead
- arsenic
- mercury
- aluminum

Could you tell me which one is correct?

mercury