Sammy and Lisa measure the mass of 3 logs. They burn the logs in a campfire, then measure the ashes. They are surprised to find that the mass of the ashes is less than the mass of the logs. How can this be explained?

The mass was compressed into ashes when the fire burned so the mass of the product was less than the mass of the reactants.

The mass was lost because there was a chemical change.

Some of the mass of the logs was turned into smoke and gasses that escaped into the air.

Mass was destroyed in the heat of the campfire.