**Core Concept**
Fishman’s index is a method used to assess the severity of pulmonary emphysema, focusing on the extent of lung damage. It involves evaluating specific sites within the lungs. The index is crucial for diagnosing and managing chronic obstructive pulmonary disease (COPD).

**Why the Correct Answer is Right**
The correct answer relates to the specific number of sites assessed in Fishman’s index. This index is significant in pulmonary medicine as it helps in quantifying the degree of emphysema. Understanding the number of sites is essential for accurately applying the index.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it underestimates the number of sites.
**Option B:** This option overestimates the number of sites evaluated in Fishman’s index.
**Option D:** Similarly, this option does not accurately represent the number of sites assessed.

**Clinical Pearl / High-Yield Fact**
Fishman’s index is a valuable tool in respiratory medicine, aiding in the assessment of emphysema severity. Remembering the correct number of sites is crucial for its application.

**Correct Answer:** C. 6 sites