The trap used for an Indian water closet is called — 

Explanation:

Traps: As the name suggests, traps simply trap the water and sewer gas. It is a plumbing device used to prevent smell, bacteria, also insects from entering your home. Different types of trap mention bellow,

• Gully trap is provided outside the building before connecting it to the external sewerage line. It also collects wastewater from the kitchen sink, washbasin, bath, and wash area.
• Intercepting trap is provided to prevent the foul gases from the public sewer from entering into the building sewer.
• Anti-siphon trap is used to prevent siphoning action.
• p trap is used with an Indian water closet. The traps are made from UPVC or cast-iron sheets. This trap also has a water seal and prevents entry of foul gases to the house.