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

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

Centrifugal condensate pumps rely on a dedicated water seal line to prevent air from leaking inward across the packing gland into the pump's vacuum side. Closing this seal line causes air infiltration, breaking suction prime and severely reducing the pump's rated discharge capacity.