Common cold is caused by

Options

A. Salmonella typhimurium
B. Corynebacterium
C. Haemophilus
D. Rhino viruses

Answer

### Step-by-Step Solution:

1. **Identify the Options**: The question provides four options:
- Salmonella typhimurium
- Corynebacterium
- Hemophilus
- Rhinovirus

2. **Evaluate Salmonella typhimurium**:
- This bacterium is known to cause typhoid fever, which is a waterborne disease.
- Since common cold is not caused by this organism, we can eliminate this option.

3. **Evaluate Corynebacterium**:
- The full name is Corynebacterium diphtheriae, which is responsible for diphtheria, also known as Klebs-Loeffler disease.
- As common cold is not caused by this bacterium, we can eliminate this option as well.

4. **Evaluate Hemophilus**:
- Hemophilus influenzae is known to cause pneumonia and is associated with respiratory diseases.
- Since it does not cause common cold, we can eliminate this option too.

5. **Identify the Correct Option - Rhinovirus**:
- Rhinovirus is the only option left.
- It is known to cause common cold, primarily transmitted through airborne droplets and affects the nasal epithelium.

6. **Conclusion**:
- The correct answer to the question "Common cold is caused by" is **Rhinovirus**.

### Final Answer:
**Rhinovirus**