Final answer:
The last ten percent of garbage in an incineration facility is predominantly ash residue. This by-product of the waste incineration process must be managed to prevent environmental harm and can sometimes be repurposed if it's sufficiently clean.
Step-by-step explanation:
The last ten percent of garbage in an incineration facility is typically c. Ash residue. Incineration is one of the two primary methods of waste disposal, the other being landfill. The incineration process reduces the original waste volume but leaves behind ash, which must be dealt with responsibly. This ash residue can contain both inert and toxic substances depending on what was incinerated. Modern facilities aim to treat and manage this residue so it does not pose a health or environmental risk. In some cases, if the ash is clean enough, it can be used as an MSW landfill cover or in the construction of roads, cement blocks, and artificial reefs. However, careful assessment is necessary to ensure the ash residue does not contain hazardous materials that could lead to environmental damage.