What substances can exit the ship’s piping system through scupper valves?

Scupper valves are designed to allow excess water or other liquids to drain out from the deck of a ship, helping to prevent flooding and maintaining stability. The correct substances that can exit through scupper valves are typically liquids that are not intended to be contained within the ship's piping system.

In this case, the combination of waste and soil as substances that can exit aligns with the function of scupper valves. Waste refers to any liquid waste generated by the ship's operations, which may contain various substances, whereas soil can refer to sediment or debris that may accumulate on deck and needs to be expelled to keep the area clear and safe.

Freshwater, on the other hand, while it can exit through scupper valves, does not serve the primary function of waste management. Fuel and oil would not appropriately be expelled through scupper valves due to environmental regulations and safety concerns. Pollen and dust are not liquids, so they do not fit the context of substances that scupper valves are designed to discharge.

Thus, the combination of waste and soil accurately represents the purpose and function of scupper valves in a ship's piping system.