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