Final answer:
The liver, stomach, mouth, and pancreas are part of the b. digestive system, which processes food and absorbs nutrients. The kidneys, mentioned for comparison, are part of the urinary system.
Step-by-step explanation:
The liver, stomach, mouth, and pancreas are part of the digestive system. The digestive system is comprised of main organs that work in succession, starting from ingestion in the mouth and ending with waste elimination. These organs form the gastrointestinal (GI) tract. Moreover, the digestive process involves accessory organs like the pancreas and liver, which produce enzymes necessary for digestion. While the kidneys do play a significant role in the body's regulation of fluids, they are a part of the urinary system, not the digestive system.
Therefore, the correct answer to the question 'The liver, stomach, mouth, and pancreas are in the _____ system.' is b. Digestive.
- The digestive system includes the mouth, esophagus, stomach, and intestines.
- Accessory organs such as the pancreas and liver produce essential digestive enzymes.
- The kidneys are involved in the urinary system, not the digestive system.