**Core Concept**
The question is testing the student's knowledge of the pathological changes that occur in the lung tissue due to certain infections. The ruffled membrane is a characteristic histopathological feature seen in a specific type of pneumonia.

**Why the Correct Answer is Right**
The ruffled membrane is a result of the epithelial lining of the alveoli becoming detached from the underlying connective tissue, leading to a characteristic "ruffled" appearance under the microscope. This occurs in pneumococcal pneumonia, caused by the bacterium *Streptococcus pneumoniae*. The bacteria produce a toxin that damages the alveolar epithelium, leading to the formation of a ruffled membrane. This is a key diagnostic feature of pneumococcal pneumonia.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because ruffled membrane is not typically associated with viral pneumonia.
**Option B:** This option is incorrect because ruffled membrane is not a characteristic feature of *Klebsiella pneumoniae* infection, which typically causes a more severe and necrotizing form of pneumonia.
**Option C:** This option is incorrect because ruffled membrane is not typically associated with fungal pneumonia.

**Clinical Pearl / High-Yield Fact**
The ruffled membrane is a classic histopathological feature of pneumococcal pneumonia and should be remembered as a key diagnostic clue in cases of pneumonia.

**Correct Answer:** D.