Which of the following is a basic valve component?

• A. Cap
• B. Gasket
• C. Stem
• D. Body

Answer: (C)

The key idea is identifying the part that actually transmits motion to regulate flow. The stem is the component that connects the actuator (like a handwheel or motor) to the valve disc or plug, so it moves the internal element up and down (or in and out) to open, close, or throttle the passage. This makes it the fundamental control element in most valve designs.

Other parts play important roles but not the primary control action. A cap is typically a cover used on some valve styles. A gasket provides a seal between mating surfaces to prevent leaks. The body forms the main exterior housing and pressure boundary of the valve. While all are essential in a valve assembly, they do not perform the moving control function that the stem provides.