In the context of mine explosions, the mixture of methane and air (Option 3) is most commonly responsible. Methane, a highly flammable gas, is commonly found in mines as it is a byproduct of the coal formation process. If trapped methane comes into contact with air, it can create an explosive mixture.

On the other hand, hydrogen and oxygen (Option 1) can indeed create an explosive mixture, but they are not commonly found in mines. Oxygen and acetylene (Option 2) also form an explosive combination and they are used in gas welding processes because of that property, but again, they are not typically found in mines. Finally, while methane is explosive, the combination of methane and carbon dioxide (Option 4) is not typically problematic. Carbon dioxide doesn`t fuel explosions; instead, it asphyxiates by displacing oxygen.

Thus, among all given options, methane and air is the correct answer as they are most involved in mine explosions.