**Core Concept**
Acute Respiratory Distress Syndrome (ARDS) is characterized by widespread alveolar-capillary membrane injury, leading to pulmonary edema and impaired gas exchange. A key pathophysiological feature is loss of lung elasticity due to collapse of alveoli and surfactant deficiency.

**Why the Correct Answer is Right**
In ARDS, alveolar collapse and fibrosis result in increased stiffness of the lung tissue. This leads to **decreased lung compliance**, meaning the lungs resist stretching and require higher pressures to inflate. This is a hallmark of ARDS and is reflected in clinical management with positive pressure ventilation. The loss of compliance is due to surfactant deficiency and pulmonary edema, not improved gas diffusion.

**Why Each Wrong Option is Incorrect**
Option A: ARDS presents with **type I respiratory failure**, not type II. Type II failure involves hypoxemia with hypercapnia due to alveolar ventilation-perfusion mismatch or ventilation-perfusion shunting, which is not the primary feature of ARDS.
Option C: Diffusion capacity is **decreased**, not increased, due to alveolar-capillary membrane thickening and edema, impairing oxygen transfer.
Option D: "None" is incorrect because **lung compliance is indeed decreased** in ARDS, making B the correct choice.

**Clinical Pearl / High-Yield Fact**
In ARDS, decreased lung compliance is a key reason for the need for mechanical ventilation with low tidal volumes and PEEP to prevent further lung injury. Remember: **"ARDS = stiff lungs, low compliance, high PEEP."**

✓ Correct Answer: B. Lung compliance decreased