What best describes a solenoid valve?

A solenoid valve is best described as an automatic gas shutoff valve. This type of valve uses an electromagnetic coil to control the opening and closing of the valve, allowing it to automate the flow of gas or fluid in a system. When electrical current passes through the coil, it generates a magnetic field that either opens or closes the valve, effectively controlling the flow without the need for manual intervention. This functionality is essential for applications requiring reliable and precise control over gas or fluid delivery, especially in safety systems where the automatic shutoff feature can prevent leaks or hazards.

The other options, such as a manual shutoff valve, pressure relief valve, and backflow prevention device, describe different functionalities that do not incorporate the automatic actuation aspect of a solenoid valve. A manual shutoff valve requires human operation to open or close, while a pressure relief valve is designed to release excess pressure in a system, and a backflow prevention device prevents reverse flow in piping systems. These distinctions highlight the unique role of a solenoid valve as an automatically operated component in various fluid handling systems.