Consider the following statements:Statement I: Studies indicate that carbon dioxide emissions from cement industry account for more than 5% of global carbon emissions.Statement II: Silica-bearing clay is mixed with limestone while manufacturing cement.Statement III: Limestone is converted into lime during clinker production for cement manufacturing.Which one of the following is correct in respect of the above statements?

1. A

   Both Statement II and Statement III are correct and both of them explain Statement I

   Both II and III correct and both explain I. The official reading keeps both lines but does not let both explain the cement-CO2 share.

2. B

   Both Statement II and Statement III are correct but only one of them explains Statement I

   Both II and III are correct, but only one explains I. Clay in the raw mix is real kiln chemistry; calcination of limestone to lime is the process-CO2 step that explains cement’s large share of global emissions.

3. C

   Only one of the Statements II and III is correct and that explains Statement I

   Only one of II and III is correct. The paper keys both as true statements.

4. D

   Neither Statement II nor Statement III is correct

   Neither. Both process lines are scored.

Summary. Official Set A key is (b). Cement is a large CO2 source (I). Silica-bearing clay is mixed with limestone in the raw meal (II) — true, but that mixing is not why cement dominates process emissions. In the kiln, limestone is calcined to lime and CO2 (III) — that process gas, plus fuel, is why I holds. So II and III are both correct, and only III (one of them) explains I.