Final answer:
All the options provided by the student—liver, stomach, small intestine, and esophagus—are parts of the digestive system. They play distinct roles in digestion, from secreting enzymes and substances to absorbing nutrients.
Step-by-step explanation:
The digestive system is a complex network of organs that work together to break down food, absorb nutrients, and eliminate waste. The main components of the digestive system include the mouth, esophagus, stomach, small intestine, and large intestine, which together form the gastrointestinal (GI) tract. Additionally, there are accessory organs such as the liver, gallbladder, and pancreas which aid digestion by producing various enzymes and substances required for the process, though food doesn't pass through these organs.
Among the options provided by the student, the liver, stomach, small intestine, and esophagus are all parts of the digestive system. The liver produces bile, which helps break down fats, while the esophagus carries food from the mouth to the stomach. The stomach further breaks down food with gastric juices, and the small intestine is where the majority of nutrient absorption occurs.