What type of pump uses a jet to create a vacuum?

The correct answer is a jet pump, which utilizes a jet of fluid to create a vacuum that can draw in additional fluid or gases. In a jet pump, fluid is forced through a nozzle, causing an increase in velocity and a corresponding decrease in pressure, thereby creating a vacuum. This vacuum can then draw in more fluid from a source, allowing for efficient pumping action. Jet pumps are commonly used in applications such as well pumping and various fluid transfer tasks, where they can efficiently move liquids.

Centrifugal pumps operate based on rotational kinetic energy rather than creating a vacuum with a jet, while piston pumps use mechanical movement and pressure differentials to move fluids, without relying on a jet action for vacuum creation. Pneumatic pumps utilize compressed air for operation, which is quite different from the principle of a jet pump. This makes the jet pump unique in its operation and function among the options provided.