Which of the following conditions is characterized by involuntary muscle contractions assisting digestion?

Peristalsis is the correct choice because it specifically refers to the series of wave-like muscle contractions that move food through the digestive tract, assisting in the process of digestion. These involuntary contractions occur in the esophagus, stomach, and intestines, allowing the contents to move smoothly along the gastrointestinal system. This rhythmic movement is essential for proper digestion and absorption of nutrients as it ensures that food is mixed with digestive enzymes and propelled toward the intestines for further processing.

The other conditions listed do not involve the same mechanism of muscle contractions for digestion. Flatus refers to gas in the digestive system, which does not involve involuntary muscle contractions shown in peristalsis. Fecal impaction is a condition where stool becomes hard and difficult to pass, leading to issues in bowel movement rather than the promotion of normal digestion. Hypoglycemia is a condition characterized by low blood sugar levels, which is unrelated to the muscular movements associated with digestion.