What happens to the size of vent pipes when washing machines and dishwashers discharge?

The correct answer focuses on the necessity for vent pipes to avoid connections to areas with suds pressure. In plumbing design, venting is crucial for maintaining proper airflow and drainage within the system. When appliances like washing machines and dishwashers discharge, they can produce suds and foam, which can create pressure in the piping system. This suds pressure can lead to a variety of issues, such as blockages and improper venting, which ultimately affect the function and efficiency of the waste and drainage system.

By avoiding connections in areas that could be affected by suds pressure, a plumber ensures that the vent system remains effective at equalizing pressure and allowing gases to escape, while also preventing any potential backflow of wastewater or suds into the vent lines. This approach helps maintain the integrity of the plumbing system, ensuring it operates as intended without the risk of negative interactions from the discharge of sudsy materials.

The other options do not address the critical impact of suds pressure on the venting of washing machines and dishwashers as effectively as this choice does. Hence, the focus on connecting vent pipes in a manner that minimizes the risk of encountering suds pressure is paramount for proper plumbing design.