The amount of suction produced during the intake stage can be measured by using a special gauge called a A. feeler. B. monometer. C. thread-pitch. D. vacuum.

The correct option is D.

Suction refers to the flow of a liquid into a partial vacuum or region of low pressure. Vacuum gauge is a device that is used to measure vacuum or sub atmospheric pressures. It is often used in conjunction with other vacuum sensors to monitor and control the vacuum pressure in a system.

I would have to say D vacuum.