Answer: A.liquid waste from a paper mill.
Step-by-step explanation:
A wastewater treatment plant is a place where reclamation of the waste water takes place. The waste water is converted into forms so that it can be used again for purposes such as irrigation, sanitation and others.
A is the correct option. This is because of the fact that the liquid waste from paper mill will have liquid which would probably contain water content. Hence, the contaminated water can be filtered in wastewater treatment plant.