Which sequence correctly lists the major sections of the human digestive tract from entry to exit?

• A. Mouth, Esophagus, Stomach, Small intestine, Large intestine
• B. Mouth, Stomach, Esophagus, Small intestine, Large intestine
• C. Mouth, Esophagus, Stomach, Large intestine, Small intestine
• D. Mouth, Esophagus, Large intestine, Stomach, Small intestine

Answer: (A)

Food enters through the mouth and is then carried down the esophagus by rhythmic muscle contractions to the stomach. In the stomach, the contents are churned and mixed with acid, starting the digestion process. The semi-liquid material then moves into the small intestine, where the bulk of digestion and nutrient absorption occurs. Finally, the remaining material passes into the large intestine, where water is absorbed and waste is formed before leaving the body through the rectum and anus. This sequence—mouth, esophagus, stomach, small intestine, large intestine—fits the actual flow of the digestive tract from ingestion to elimination.