Final answer:
Chyme is a mixture of partly digested food and gastric juices including digestive enzymes and acids from the stomach. It enters the duodenum through the pyloric sphincter, where it continues to be broken down by bile and other digestive juices.
Step-by-step explanation:
Chyme can be described as a semi-liquid mass of partly digested food that is produced by the stomach and delivered into the duodenum. It is correctly characterized by being food mixed with digestive enzymes (a), resulting from the breakdown of food into a small mass in the oral cavity before reaching the stomach (b), and also as the substance that exits the stomach and enters the duodenum via the pyloric sphincter (c). However, it is not described as food mixed with acids secreted by the stomach; while chyme does contain gastric acid, the phrase is slightly misleading since it lacks the critical aspect of partial digestion that defines chyme. When chyme enters the duodenum, it is mixed with bile and pancreatic juices that further assist in digestion.