When fuel X is burnt in air, it forms carbon dioxide and water. Fuel Y does the same. What might X and Y be?
- AX: C; Y: $\text{H}_2$
- BX: C; Y: $\text{C}_8\text{H}_{18}$
- CX: $\text{CH}_4$; Y: $\text{H}_2$
- DX: $\text{CH}_4$; Y: $\text{C}_8\text{H}_{18}$