Liquid is kept from leaking out at the shaft ends of a helical gear pump by __________.

Correct Answer: Option B — a stuffing box

Helical gear pumps are positive displacement units that require a stuffing box at the shaft penetration point to prevent leakage. The stuffing box houses packing rings compressed by a gland, which creates a seal against the rotating shaft, ensuring the pumped fluid remains contained within the pump casing.