What is a pump?

A pump is fundamentally defined as a device that moves fluids or gases through mechanical action. This definition encapsulates the primary function of a pump, which is to create flow and facilitate the movement of various materials, such as water, oil, or even gases. Pumps achieve this through mechanisms like positive displacement, where the volume of fluid is trapped and pushed forward, and dynamic pumping, where fluid is accelerated using rotors or impellers.

The mechanical action utilized by pumps can vary widely, but its core role is to bring about fluid movement, whether it's supplying water to a facility, circulating coolant in a process, or transporting chemicals across various industries. Understanding this operational principle is vital for recognizing how pumps are integrated into systems for efficient fluid handling.

In this context, the other options do not accurately define a pump. While measuring pressure, cooling fluid, and filtering liquids are important tasks in various systems, they do not encompass the primary function of a pump. Hence, the correct characterization recognizes a pump's role in fluid or gas movement as its essential operation.