**Core Concept**
Angioedema is a severe, life-threatening form of allergic reaction characterized by rapid swelling of the skin and mucous membranes. It involves the increased permeability of blood vessels, leading to fluid leakage into the surrounding tissues.

**Why the Correct Answer is Right**
The etiology of angioedema is multifactorial, but it primarily involves the activation of the kinin-kallikrein system, which leads to the production of bradykinin. Bradykinin is a potent vasodilator that increases vascular permeability, causing fluid to leak into the interstitial space. This results in the characteristic swelling seen in angioedema. The bradykinin also stimulates the release of histamine from mast cells, further contributing to the inflammation and edema.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not accurately describe the primary etiology of angioedema. While histamine release is a contributing factor, it is not the main cause of angioedema.

**Option B:** This option is incorrect as it is more related to the pathophysiology of anaphylaxis rather than angioedema. While both conditions involve the release of histamine and other mediators, the primary mechanism of angioedema involves the kinin-kallikrein system.

**Option C:** This option is incorrect as it describes a secondary effect of angioedema rather than the primary etiology. The increased vascular permeability and fluid leakage into the interstitial space lead to swelling, but this is a result of the underlying pathophysiological process, not the cause.

**Clinical Pearl / High-Yield Fact**
The kinin-kallikrein system plays a central role in the pathophysiology of angioedema. Understanding this mechanism is crucial for the diagnosis and management of angioedema.

**Correct Answer: C. Increased vascular permeability due to bradykinin release.**