A river's water quality improves after a new wastewater treatment plant is built. What is the most probable cause?
Q1. A river's water quality improves after a new wastewater treatment plant is built. What is the most probable cause?
Answer: New wastewater treatment plant
Explanation: New wastewater treatment plants directly improve water quality by treating effluent. Stricter regulations can lead to improved water quality but are not the direct cause here.