Where do certain symboitic microorganisms normally occur in human body

Options

A. Oral lining and tongue surface
B. Vermiform appendix and rectum
C. Duodenum
D. Caecum

Explanation

### Step-by-Step Solution:

1. **Understanding Symbiotic Microorganisms**: Symbiotic microorganisms are those that live in a close association with the human body, often providing benefits such as aiding in digestion or synthesizing vitamins.

2. **Identifying Locations in the Human Body**: The question asks where these microorganisms are typically found. The key areas to consider are:
- Oral lining and tongue surface
- Vermiform appendix and rectum
- Duodenum
- Cecum

3. **Analyzing Each Location**:
- **Oral Lining and Tongue Surface**: While there are microorganisms present in the mouth, they primarily aid in digestion through enzymes and secretions rather than being symbiotic in nature.
- **Vermiform Appendix and Rectum**: The vermiform appendix is part of the immune system, and the rectum is primarily involved in waste elimination. Neither is known for hosting significant populations of symbiotic microorganisms.
- **Duodenum**: This is the first part of the small intestine where digestion and absorption occur, but it does not host a significant number of symbiotic microorganisms.
- **Cecum**: The cecum is a part of the large intestine and is known for hosting a variety of symbiotic microorganisms. It plays a role in the synthesis of vitamins (like B12) and aids in digestion.

4. **Conclusion**: Based on the analysis, the cecum is the primary location in the human body where symbiotic microorganisms are found.

### Final Answer:
The cecum is the part of the human body where certain symbiotic microorganisms normally occur.

---