Final Answer:
A combination waste and vent system limits the number of fixtures allowed on the system. Option B is the answer.
Step-by-step explanation:
A combination waste and vent system in plumbing serves the dual purpose of carrying wastewater away from fixtures and providing venting to prevent trap siphonage. The system is designed with limitations, and in this context, it restricts the number of fixtures that can be connected to it. Fixtures include sinks, toilets, showers, and other drainage points in a building. The system is engineered to ensure proper drainage and ventilation, preventing issues such as airlocks or slow drainage.
This limitation on the number of fixtures helps maintain the efficiency and functionality of the combination waste and vent system, ensuring that it can effectively handle the wastewater and maintain proper ventilation for each connected fixture.
Option B is the answer.