What are the five layers of the gastrointestinal (GI) tract in order from inner to outer?

The correct answer outlines the five layers of the gastrointestinal (GI) tract in the appropriate sequence. Starting from the innermost layer, the mucosa is the innermost lining that functions primarily in absorption and secretion. Next is the submucosa, which is composed of connective tissue that contains blood vessels, nerves, and glands, providing the necessary support and nourishment to the mucosa. Following this, the muscularis layer is responsible for the coordinated contractions that facilitate peristalsis, aiding the movement of food through the digestive system. The outermost layer mentioned as the serosa is a smooth membrane that reduces friction between the digestive organs and surrounding structures.

Even though mesothelium is a type of tissue found lining the cavities of the body, it is not considered one of the distinct layers of the GI tract. The correct layers do not include adventitia or other incorrect sequences listed in the other options. Thus, in the context of the anatomy of the GI tract, the order and naming of the layers in the selected answer accurately reflects the accepted biological structure.