Answer the following question given this paragraph: 

Behind each release of gas is an army of gut bacteria undergoing some crazy biochemistry. These bacteria break down the remains of digested food through fermentation, creating gas in the process. Learn what these bacteria have in common with beer brewing at http://youtu. be/R1kxajH629A?list=PLzMhsCgGKd1hoofiKuifwy6qRXZs7NG6a .


Q: Bacteria break down the remains of digested food through a processed called what?

 Choices:

- regulation

- oxidation

- synthesis

- fermentation

A:
fermentation
