The correct answer is (A)
Burning of wood is a chemical change as new substance is formed during the burning of wood which is not reversible.
Now, what happened during the burning of wood?
In the case of burning wood, stored potential energy( in the form of chemical energy) in the log is released due to heating by other excited atoms. This chemical reaction is called combustion that requires oxygen. We can also say that combustion is change of potential chemical energy into kinetic energy in the form of heat.