The correct answer is D) Inspection of the hold at completion of discharge. Overcarriage refers to a situation where cargo remains on board after the vessel has been unloaded, which can lead to the vessel becoming unstable or overloaded. The best way to prevent overcarriage is to thoroughly inspect the hold at the completion of cargo discharge to ensure all cargo has been removed. This allows the crew to identify and address any remaining cargo before the vessel departs. The other options, while potentially helpful, do not directly address the issue of overcarriage. Stowing heavy cargo low in the vessel (A) and stowing cargo to be discharged last on the bottom (B) can help manage the vessel's stability, but do not prevent overcarriage itself. Checking load line calculations (C) is important for determining the vessel's maximum safe loading, but does not directly address the problem of cargo left behind after unloading.