Why is there a concern about copper smelting plants? 1. They may release lethal quantities of carbon monoxide into environment. 2. The copper slag can cause the leaching of some heavy metals into environment. 3. They may release sulphur dioxide as a pollutant. Select the correct answer using the code given below.

Defines CO as a product of incomplete burning of carbon-based fuels (petrol, diesel, wood) and notes its toxic effect on human oxygen uptake.

A student can infer that any industrial process using carbonaceous fuels (e.g., for smelting furnaces) could produce CO if combustion is incomplete, so one should check whether smelters use such fuels and monitor CO near furnaces.

Describes roasting of sulphide ores by strong heating in air as a step in converting sulphides to oxides prior to metal extraction.

A student could link high‑temperature ore processing (roasting/smelting) to potential combustion/chemical gas emissions and thus seek studies measuring CO and other gases from roasting/smelting operations.

Lists carbon monoxide among common man‑made air pollutants associated with combustion sources in urban/industrial contexts.

Use this pattern to suspect industrial plants (including metal works) as potential CO sources and then check location‑specific emission inventories or ambient CO measurements near smelters.

Mentions an actual copper plant (Tajola Copper Plant), establishing that copper smelting/processing facilities exist as local industrial sources.

Combine awareness of actual plants with the combustion/roasting clues above to target those specific plants for emission measurements or regulatory records on CO emissions.

Refers to smokestacks and combustion sources emitting various gases and groups CO/CO2 with combustion emissions.

Suggests consulting smokestack emission profiles or environmental impact assessments for smelters to see whether CO is reported and at what concentrations.