Peristalsis is defined as:

• A. The mixing of food with digestive juices.
• B. Movement of food from the mouth to the esophagus.
• C. Alternating contractions that mix food in the intestines.
• D. Muscular waves that move food through the GI tract.

Answer: (D)

Verified step by step guidance

1. Understand the term 'peristalsis': It refers to the involuntary, rhythmic, wave-like contractions of the smooth muscles in the gastrointestinal (GI) tract that propel food along the digestive system.
2. Differentiate peristalsis from other digestive processes: For example, mixing food with digestive juices involves segmentation, not peristalsis. Similarly, the movement of food from the mouth to the esophagus is swallowing, not peristalsis.
3. Focus on the key characteristic of peristalsis: It involves muscular waves that move food through the GI tract, starting from the esophagus and continuing through the stomach, intestines, and beyond.
4. Eliminate incorrect options: The other options describe different processes (e.g., mixing food or swallowing) and do not match the definition of peristalsis.
5. Select the correct answer: Based on the definition and process of peristalsis, the correct answer is 'Muscular waves that move food through the GI tract.'