Final answer:
Pancreatic juice is a slightly alkaline secretion that helps neutralize the acidity of chyme entering the small intestine from the stomach.
Step-by-step explanation:
The slightly alkaline secretion that helps neutralize the acidity of chyme entering the small intestine from the stomach is pancreatic juice. Pancreatic juice contains sodium bicarbonate, which is responsible for its alkalinity. The bicarbonate in the juice helps buffer the acidic gastric juice in chyme, inactivate pepsin from the stomach, and create an optimal environment for the activity of pH-sensitive digestive enzymes in the small intestine.