How is pump capacity rating typically obtained?

The correct choice indicates that pump capacity rating is typically determined at a specific combination of lift and hard sleeve conditions. Specifically, a pump's capacity is often rated at 10 feet of lift and utilizing a 20-foot hard sleeve. This scenario describes a realistic operational condition that a pump might encounter in the field, allowing for a practical assessment of its performance capabilities.

In essence, when pumps are tested or rated under these conditions, it ensures that the results reflect how the pump would function in real-world applications where it is required to draw water from a source and deliver it effectively through a length of hose or hard sleeve. This approach also accounts for the physical influences of the lift required to draw the water and the friction losses associated with the hose.

The other options may not provide the representative conditions under which pumps operate effectively or might involve discrepancies in lift and sleeve lengths that do not mirror typical operational scenarios. Thus, focusing on standard measurements with an understanding of practical lifting and delivery conditions assists in making accurate assessments of pump capacity.