The correct answer is D. suspended particulate matter.
Gravity setting chambers are used to remove suspended particulate matter from air streams. They are typically used in industries where there is a lot of dust or other particulate matter in the air, such as mining, power generation, and manufacturing.
The chamber consists of a large, open tank with a sloping bottom. The air stream enters the tank at the top and flows down the slope. As the air flows down, the heavier particulate matter falls out of the air and settles to the bottom of the tank. The clean air then exits the tank at the top.
Gravity setting chambers are a simple and effective way to remove suspended particulate matter from air streams. They are relatively inexpensive to operate and maintain, and they do not require any chemicals or other treatment.
The other options are incorrect because:
- NOx (nitrogen oxides) are gases that are formed when fossil fuels are burned. They can cause respiratory problems and other health issues.
- SOx (sulfur oxides) are also gases that are formed when fossil fuels are burned. They can cause acid rain and other environmental problems.
- CO (carbon monoxide) is a gas that is produced when fossil fuels are burned incompletely. It is a poisonous gas that can cause death if inhaled in high concentrations.