The correct answer is: A. House sewers.
House sewers are the smallest pipes in the sewerage system. They collect wastewater from sinks, toilets, and showers in a home and carry it to the main sewer line.
Lateral sewers are larger pipes that collect wastewater from house sewers and carry it to branch sewers.
Branch sewers are even larger pipes that collect wastewater from lateral sewers and carry it to main sewers.
Main sewers are the largest pipes in the sewerage system. They collect wastewater from branch sewers and carry it to treatment plants.
Here is a diagram of a typical sewerage system:
As you can see, house sewers are the first step in the sewerage system. They collect wastewater from sinks, toilets, and showers in a home and carry it to the main sewer line. The main sewer line then carries the wastewater to a treatment plant, where it is cleaned and then released back into the environment.
I hope this helps!