The correct answer is: A. Vent pipe
A vent pipe is a pipe that is installed in the house drainage to preserve the water seal of traps. It is a vertical pipe that is connected to the drain pipe and extends above the roof. The vent pipe allows air to enter the drainage system, which prevents the water seal from being broken.
A waste pipe is a pipe that carries wastewater from the house to the sewer line. It is a horizontal pipe that is connected to the drain pipe and extends to the sewer line.
A soil pipe is a pipe that carries sewage from the house to the sewer line. It is a vertical pipe that is connected to the drain pipe and extends to the sewer line.
An anti-siphonage pipe is a pipe that is installed in the house drainage to prevent the water seal from being broken when the water level in the trap drops below the level of the drain opening. It is a horizontal pipe that is connected to the drain pipe and extends to the trap.