Final answer:
Lake Apopka in Florida is the famous case study that describes how a heavily polluted lake was remediated and is now used for recreation.
Step-by-step explanation:
The correct answer is Option D: Lake Apopka in Florida.
Lake Apopka is a famous case study in the United States that describes how a very polluted lake was able to be remediated and is now used for recreation by many people.
It was once heavily polluted due to agricultural runoff, leading to high levels of nutrients and toxic substances in the water. However, extensive restoration efforts, including the reduction of nutrient inputs and the restoration of wetlands, have improved the water quality and ecosystem health of Lake Apopka.