B .pure water it’s made up of oxygen and hydrogen “H2O”
Because you are never adding more than the substances created, nor are you creating any, but should a chemical reaction take place you could see the liquid change form into a gaseous state and that would result a loss of the liquid volume.
So to wrap it all up you can’t have more liquids than what is already there but you could always lose some due to a chemical change, hence the reason it says an open flask, the chemical change would not be collected, mass would be lost
in order for a scientific theory to become a scientific law it needs to be tested with generations of data to confirm that it is really true.
I believe it is C, Chemical energy because of the changes in the gasoline burning, and mechanical energy because the wheels are moving.
