Final answer:
The only category of trash that can be thrown overboard on inland waters is food waste, as it is biodegradable and decomposes naturally, unlike plastics, metal, or glass.
Step-by-step explanation:
The category of trash that can be thrown overboard on inland waters is D) Food waste. Food waste is biodegradable and can be broken down by natural processes. Unlike plastics, metal, or glass, which persist in the environment and can cause harm to aquatic life, properly disposed food waste will decompose naturally. Aquatic debris can strangle, entangle, or be mistaken for food by wildlife, leading to injury or death. Therefore, disposing of food waste in a responsible manner is the best practice when managing trash on inland waters. However, it is essential to further investigate local regulations, as some areas might have specific rules against discarding any types of waste into waterways.