**Core Concept**
Volkmann's contracture is a deformity of the hand, fingers, and wrist caused by injury to the forearm. It results from a lack of blood flow to the forearm muscles, leading to muscle ischemia and subsequent fibrosis. This condition is often associated with compartment syndrome.

**Why the Correct Answer is Right**
The correct answer is related to the anatomy of the forearm. The artery responsible for supplying blood to the forearm muscles is the **radial artery**. In compartment syndrome, the increased pressure within the forearm compartment can compromise the flow through the radial artery, leading to ischemia and muscle damage. This is the underlying pathophysiological mechanism behind Volkmann's contracture.

**Why Each Wrong Option is Incorrect**
* **Option A:** The ulnar artery is another artery supplying the forearm but it is not primarily responsible for Volkmann's contracture.
* **Option B:** The brachial artery is the main artery supplying the arm but it is not directly related to Volkmann's contracture.

**Clinical Pearl / High-Yield Fact**
The 6 Ps of compartment syndrome are: pain, pallor, pulselessness, paresthesia, poikilothermia, and paralysis. These symptoms can help identify compartment syndrome, which is a medical emergency requiring prompt treatment.

**Correct Answer:** A. Radial artery.