Final answer:
The function of rugae is to help the stomach expand when necessary, allowing it to accommodate more food and liquid as it fills.
Step-by-step explanation:
The function of rugae in the stomach is A. They help the stomach expand when necessary. Rugae are prominent folds in the stomach lining that allow for expansion as the stomach fills with food.
Rugae serve as functional features in the stomach to accommodate the volume changes that occur when food enters the organ. They are similar to folds or wrinkles and flatten out as the stomach expands, allowing it to hold a significantly larger amount of food and liquids than would be possible if the inner lining was rigid.
This capability is essential since the stomach acts as a temporary storage site, regulating the passage of food into the small intestine for further digestion. Rugae are not directly involved in muscle contractions for churning; this is managed by the muscular walls of the stomach. Nor are they primarily responsible for secreting enzymes or mucus, functions carried out by specialized cells within the gastric glands.