Duct leading from parotid gland and opening into vestibule is

Options

A. Haversian duct
B. Stenson's duct
C. Wolffian duct
D. Infra-orbital duct,

Explanation

To solve the question regarding the duct leading from the parotid gland and opening into the vestibule, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Gland**: The question mentions the parotid gland, which is known as the largest salivary gland in the human body. Understanding the role of the parotid gland is crucial.

2. **Function of the Parotid Gland**: The primary function of the parotid gland is to secrete saliva. This saliva plays an essential role in digestion and oral health.

3. **Ducts Associated with Salivary Glands**: Salivary glands have ducts that transport saliva from the gland to the oral cavity. Each salivary gland has its specific duct.

4. **Identify the Correct Duct**: The duct that leads from the parotid gland is specifically known as Stenson's duct. This duct carries saliva from the parotid gland and opens into the vestibule of the mouth, which is the area between the gums and the inner lining of the lips.

5. **Evaluate the Options**: The options given are:
- a. Haversian duct
- b. Stenson's duct
- c. Wolfian duct
- d. Infraorbital duct

Among these options, Stenson's duct is the only one that is associated with the parotid gland.

6. **Conclusion**: Therefore, the correct answer to the question is **b. Stenson's duct**.

### Final Answer:
**b. Stenson's duct**