An example of an industrial waste is:

An example of an industrial waste is:

• A. mining waste
• B. oil and gas production waste
• C. wastewater treatment sludge
• D. iron and steel manufacturing waste

Answer: (D)

Industrial waste comes from manufacturing and processing activities, not from extraction or municipal systems. Iron and steel manufacturing waste is a clear example because steel production involves high‑temperature processing that leaves solid residues—slag, mill scale, dust, and other byproducts—directly from a manufacturing plant. These residues arise from the industrial operation itself, making them quintessential industrial waste. The other options are tied more to extraction or treatment of waste rather than the manufacturing process itself. Mining waste comes from extracting raw materials, oil and gas production waste from hydrocarbon extraction and processing, and wastewater treatment sludge typically originates from treating wastewater rather than from a manufacturing process.

Industrial waste comes from manufacturing and processing activities, not from extraction or municipal systems. Iron and steel manufacturing waste is a clear example because steel production involves high‑temperature processing that leaves solid residues—slag, mill scale, dust, and other byproducts—directly from a manufacturing plant. These residues arise from the industrial operation itself, making them quintessential industrial waste.

The other options are tied more to extraction or treatment of waste rather than the manufacturing process itself. Mining waste comes from extracting raw materials, oil and gas production waste from hydrocarbon extraction and processing, and wastewater treatment sludge typically originates from treating wastewater rather than from a manufacturing process.