The pathogen Haemophilus influenzae is responsible for the disease:

Options

A. Influenza
B. Pneumonia
C. Plague
D. Diphtheria

Answer

**Step-by-Step Solution:**

1. **Identify the Pathogen**: The question asks about the pathogen Haemophilus influenzae. This is a bacterium that can cause various diseases.

2. **Evaluate the Options**:
- **Option A: Influenza**: This is a viral disease caused by the influenza virus, not by Haemophilus influenzae. Therefore, this option is incorrect.
- **Option B: Pneumonia**: Haemophilus influenzae is known to cause pneumonia, particularly in young children and individuals with weakened immune systems. This option is correct.
- **Option C: Plague**: The plague is caused by the bacterium Yersinia pestis, not Haemophilus influenzae. Thus, this option is incorrect.
- **Option D: Diphtheria**: Diphtheria is caused by Corynebacterium diphtheriae, which is also not related to Haemophilus influenzae. Therefore, this option is incorrect.

3. **Conclusion**: Based on the evaluation of the options, the disease caused by the pathogen Haemophilus influenzae is pneumonia.

**Final Answer**: The pathogen Haemophilus influenzae is responsible for the disease pneumonia.

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