The correct answer is C) Gravity tank overflow lines are lead directly to the lube oil sump. In a gravity-type lube oil system, the overflow from the gravity tanks is typically routed directly to the lube oil sump or drain tank. This ensures that any excess oil in the gravity tanks is safely returned to the system rather than creating a potential spill or leakage issue. The other options are incorrect: A) The discharge from the gravity tanks flows to the lube oil pump suction, not directly to the sump. B) Lube oil pump failure may cause damage, but this is not an immediate effect. D) Gravity tanks are not typically fitted with overflow alarms, as the overflow line to the sump provides a safe discharge path.