root beerr
Ginger Ale, actually, which was the original soda pop invented and first sold in 1862.
coke
most likely because soda tends to fizz more on dry, uneven surfaces.
pepsi
Currently Pepsi.
One way to demonstrate the fizz in soda is to connect balloons to the top of a soda bottle. The next step is to measure the inflation of the balloon to find "fizz". Then record your data.
frecsa
The fizz is put into soda by pumping carbon dioxide into it under pressure.
Cream Soda
diet coke.
Carbon dioxide gas puts the fizz in soda water.
From my personal experience, Coca-Cola has had the most amount of fizz.
Baking Soda is most likely the answer to this question.