**Core Concept**
The question is testing the knowledge of secretions with unique pH properties. Gastric and pancreatic secretions have distinct pH levels due to the presence of enzymes and bicarbonate ions. This is crucial for digestion and protection of the mucosal lining.

**Why the Correct Answer is Right**
The correct answer is pancreatic juice, which has a very high pH due to the presence of bicarbonate ions (HCO3-) secreted by the pancreas. These bicarbonate ions help neutralize the acidic chyme from the stomach, creating an optimal environment for pancreatic enzyme activity. The bicarbonate ions are produced in the pancreatic ductal cells and are secreted into the pancreatic juice, which has a pH range of 8-9.

**Why Each Wrong Option is Incorrect**
**Option A:** Gastric juice has a low pH (1.5-3.5) due to the presence of hydrochloric acid (HCl) secreted by the parietal cells, making it an acidic environment.

**Option B:** Saliva has a neutral pH (around 6.5-7.5) due to the presence of bicarbonate ions and enzymes, but it is not as alkaline as pancreatic juice.

**Option C:** Bile has a slightly alkaline pH (around 7.5-8.5) due to the presence of bicarbonate ions, but it is not as alkaline as pancreatic juice.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the pH of pancreatic juice is crucial for the activation of pancreatic enzymes, such as amylase and lipase, which are essential for carbohydrate and fat digestion.

**Correct Answer:** C. Pancreatic juice has a very high pH.