**Core Concept**
The finger in glove sign is a radiological finding that refers to the appearance of the lung parenchyma on a chest radiograph, where the lung markings resemble the fingers of a glove. This sign is indicative of pulmonary edema, specifically cardiogenic pulmonary edema.

**Why the Correct Answer is Right**
The finger in glove sign is seen in conditions where there is an increase in pulmonary interstitial fluid, leading to the appearance of Kerley B lines on a chest radiograph. These lines are short, horizontal lines that represent fluid-filled interlobular septa. The increased fluid in the lungs leads to the characteristic "finger in glove" appearance. This sign is often associated with cardiogenic pulmonary edema, where the left ventricle is unable to pump blood efficiently, leading to fluid accumulation in the lungs.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the finger in glove sign is not typically associated with obstructive lung diseases, where the primary issue is airflow limitation rather than fluid accumulation in the lungs.
* **Option B:** This option is incorrect because the finger in glove sign is not a characteristic finding in pneumonia, where the primary issue is inflammation of the lung parenchyma.
* **Option C:** This option is incorrect because the finger in glove sign is not typically associated with pulmonary embolism, where the primary issue is blockage of a pulmonary artery.

**Clinical Pearl / High-Yield Fact**
The finger in glove sign is a classic radiological finding in cardiogenic pulmonary edema, and it is often accompanied by other signs such as Kerley B lines, upper lobe diversion, and perihilar opacities.

**Correct Answer: D**