What type of pump is designed to pump only fluids, without any air?

Answer: C — Centrifugal Pump

The type of pump that is specifically designed to pump fluids and effectively excludes air from the process is the positive-displacement pump. This type of pump functions by trapping a fixed amount of fluid and then forcing it through the discharge pipe. This mechanism is particularly effective for applications requiring a consistent flow rate and volume, regardless of the pressure in the discharge line. Positive-displacement pumps can effectively handle various types of fluids, including those that may contain solid particles or have varying viscosities. Their design inherently minimizes the chances of air being mixed with the liquid being transported, ensuring a reliable and continuous flow. While other types of pumps, such as centrifugal and rotary pumps, can move fluids, they may be more susceptible to introducing air into the system, especially if not properly primed or in specific operating conditions. Piston and rotary pumps also fall under the broader category of positive-displacement pumps, but the key distinguishing feature of the question pertains to the type specifically focused on efficiently moving liquids without air, which aligns with positive-displacement technology.