The correct option is C Both A and B
A chemical equation can convey the physical state of reactants and products, reaction conditions and the energy transfer in a chemical reaction using appropriate symbols or abbreviations.
In the given reaction
2H2 (g) + O2 (g) →2H2O (g)
Only the physical states of the reactants and products are represented using the symbol (g). Energy transfer is not represented. Hence, A and B conditions are correct, ie. option C.