Question

which impurity in fossil fuels can bioaccumulate and cause harm in aquatic systems? helium oxygen ozone mercury

Explanation:

Helium is an inert gas, oxygen is essential for aquatic life, and ozone is mainly in the atmosphere. Mercury is a toxic heavy metal impurity in fossil fuels. When fossil fuels are burned, mercury is released, enters aquatic systems, and bioaccumulates in organisms (like through the food chain), causing harm.

Answer:

D. mercury