Assertion (A): The Ellingham line for $\mathrm{C}+\mathrm{O}{}_2\to \mathrm{CO}{}_2$ is almost horizontal. Reason (R): In this reaction the number of moles of gas does not change, so $\Delta S^{\circ }$ is very small. Choose:

1. ABoth A and R are true and R is the correct explanation of A
2. BBoth A and R are true but R is not the correct explanation of A
3. CA is true but R is false
4. DA is false but R is true