**Core Concept**
Smothering is a form of asphyxia caused by obstruction of the airway, leading to a reduction in oxygen levels. The postmortem findings in smothering can be subtle and may not always be immediately apparent.

**Why the Correct Answer is Right**
The postmortem finding in smothering is often the absence of vital reaction around the mouth and nostrils, indicating a lack of struggle or respiratory effort. This is due to the fact that the individual may have been unconscious or unresponsive at the time of death, preventing the typical vital reaction seen in other forms of asphyxia. Additionally, the lungs may show congestion and edema, but these findings are not unique to smothering and can be seen in other types of asphyxia as well.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it is a finding more commonly associated with hanging, where the presence of vital reaction around the neck indicates a struggle or attempt to free oneself.
* **Option B:** This option is incorrect because it is a finding more commonly associated with drowning, where the lungs are typically heavy and waterlogged due to the inhalation of water.
* **Option C:** This option is incorrect because it is a finding more commonly associated with strangulation, where the presence of vital reaction around the neck indicates a struggle or attempt to free oneself.

**Clinical Pearl / High-Yield Fact**
In cases of suspected smothering, it is essential to look for the absence of vital reaction around the mouth and nostrils, as well as the presence of congestion and edema in the lungs.

**Correct Answer: D.**