Which of the following shows a valid combustion reaction?

2Al + 2O2 → 2AlO + O2

C2H4 + 2O2 → 2CO2 + 2H2O

2CH4 + O2 → 2CO + 4H2

Ca + O2 → CaOH

Generally a combustion reaction is one in which a hydrocarbon burns completely in the presence of oxygen to form carbon dioxide and water. In other words, all the carbon's gets converted to CO2 while all the hydrogen's get converted H2O.

Thus, based on the given options reaction of ethylene with oxygen is a valid combustion reaction

C2H4 + 2O2 → 2CO2 + 2H2O