Which of the conditions listed could prevent a centrifugal condensate pump from developing its rated capacity?

Correct Answer: Option B — Closing the water seal line to the packing gland.

Centrifugal condensate pumps operate under vacuum. Closing the water seal line allows air to leak into the pump casing through the packing gland. This air infiltration causes cavitation and air binding, significantly reducing the pump's ability to develop rated capacity, as established in standard marine centrifugal pump operating principles.