Correct Answer: Rugae

Solution : The correct answer is Rugae.

Rugae are the finger like folds found in the lining of stomach. They are responsible for elasticity of stomach and helps it to store more food in it. Stomach has a pH of about 1.5 to 3 because of hydrochloric acid present in it and the parietal cells of stomach are responsible for the release of gastric juices.

Microvilli are the folds found in small intestine which increase the absorptive surface area of intestine for absorption of necessary nutrients.