The protection provided by the mucous membrane against pathogenic invasion is not enough. The mere ingestion of tubercle bacilli or picornaviruses in sufficient numbers will lead to penetration of GIT mucosa. A similar penetration of respiratory tract by___ can occur following a heavy exposure to these pathogens :

Options

A. Pneumococci
B. Rhinoviruses
C. Salmonella
D. Both 1 and 2

Answer

To solve the question regarding the penetration of the respiratory tract by pathogens following heavy exposure, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question states that the mucous membrane provides some protection against pathogens, but this protection can be compromised with heavy exposure. We need to identify which pathogens can penetrate the respiratory tract under such conditions.

2. **Identify the Pathogens**: The options provided are:
- Pneumococci
- Rhinoviruses
- Salmonella
- Both 1 and 2 (which refers to pneumococci and rhinoviruses)

3. **Analyze Each Option**:
- **Pneumococci**: These are bacteria that can cause pneumonia and are known to penetrate the respiratory tract, especially under conditions of heavy exposure.
- **Rhinoviruses**: These are viruses that are commonly associated with the common cold and can also penetrate the respiratory tract.
- **Salmonella**: This is primarily associated with gastrointestinal infections and does not typically penetrate the respiratory tract.

4. **Determine the Correct Answer**: Since both pneumococci and rhinoviruses can penetrate the respiratory tract following heavy exposure, the correct answer is "both 1 and 2".

5. **Final Answer**: The correct answer to the question is "both 1 and 2".