Final answer:
Granules given during a GI series can produce gases like hydrogen, carbon dioxide, and methane through bacterial fermentation in the large intestine.
Step-by-step explanation:
During a GI series, granules are often given to assess the normal function of the gastrointestinal tract. These granules can contain substances like radioactive fatty acids, iron (59Fe), or vitamin B₁2. When these granules are ingested and broken down in the digestive system, they can produce gases such as hydrogen, carbon dioxide, and methane. This gas production occurs in the large intestine through the process of saccharolytic fermentation by bacteria, resulting in the discharge of flatus or gas.