Final answer:
A low heel inlet bend is designed for the 90° connection between a water closet and a trap arm or fixture drain, enhancing the flow rate by reducing turbulence.
Step-by-step explanation:
The device referred to in the question is a low heel inlet bend. This is specifically designed to make the 90° bend that connects a water closet to a trap arm or fixture drain. The purpose of the low heel inlet is to streamline the flow of waste into the drain system, while also allowing for venting of the system to prevent negative air pressure, which can slow down the drainage process or cause gurgling noises. Devices like this increase the flow rate by providing a smoother transition for water to move through the piping, which reduces turbulence and potential blockages. The correct answer to complete the sentence is a: low heel inlet 1/4.