Only 1, 2, and 6 can be some of the reactants and products in the same reaction.
The general form of a combustion is
Elements + O_2 → oxides of elements
In 1, 2, 6 we have
Elements + O_2(2) → CO_2(3) + H_2O(6)
“Elements” could be a compound containing C and H. For example,
CH_4 + 2O_2 → CO_2 + 2H_2O