Answer:
b)eutrophication
Step-by-step explanation:
have you ever seen a lake or body of water with a layer of green on top? That's eutrophication due to heavy amounts of growth nutrients (primarily from runoffs from agriculture) in water. Simple plants utilize those and grow very fast. As they grow, they take up the oxygen and make water oxygen poor. These produce deadzones cuz the water life basically suffocates to death due to less oxygen. Eventually plants will also die