**Core Concept**
Acute Respiratory Distress Syndrome (ARDS) is a life-threatening condition characterized by rapid onset of non-cardiogenic pulmonary edema, leading to hypoxemic respiratory failure. It occurs in critically ill patients, often as a result of severe trauma, sepsis, or pneumonia. Key features of ARDS include bilateral infiltrates on chest radiographs, hypoxemia, and a ratio of arterial oxygen tension to fractional inspired oxygen (PaO2/FiO2) less than 300 mmHg.

**Why the Correct Answer is Right**
ARDS is characterized by increased permeability of the pulmonary capillary endothelium and alveolar epithelium, leading to fluid and protein leakage into the alveolar space. This results in impaired gas exchange, hypoxemia, and respiratory failure. The pathophysiology of ARDS involves the activation of inflammatory cells, release of cytokines, and upregulation of adhesion molecules, ultimately leading to increased vascular permeability and edema. Key features of ARDS include bilateral infiltrates on chest radiographs, hypoxemia, and a ratio of PaO2/FiO2 less than 300 mmHg.

**Why Each Wrong Option is Incorrect**
**Option A:** Not applicable, as there is no information provided.
**Option B:** Not a feature of ARDS, as it is not a hallmark of the condition.
**Option C:** Not a feature of ARDS, as it is not a characteristic of the condition.
**Option D:** Not a feature of ARDS, as it is not a defining characteristic of the condition.

**Clinical Pearl / High-Yield Fact**
A key feature of ARDS is the presence of bilateral infiltrates on chest radiographs, which can be seen in the context of sepsis, trauma, or pneumonia. The Berlin Definition of ARDS classifies the condition into three subtypes based on the severity of hypoxemia: mild (200 mmHg < PaO2/FiO2 < 300 mmHg), moderate (100 mmHg < PaO2/FiO2 < 200 mmHg), and severe (PaO2/FiO2 < 100 mmHg). **Correct Answer: B.**