**Core Concept**
Fracture clavicle, also known as a broken collarbone, is a common injury that affects the clavicle bone, which connects the shoulder blade to the breastbone. The clavicle plays a crucial role in shoulder stability and movement.

**Why the Correct Answer is Right**
The correct answer is D) Due to fall on outstretched hand. This type of injury occurs when a person falls onto an outstretched hand, causing a direct blow to the clavicle. This mechanism of injury is the most common cause of clavicle fractures. The clavicle is a long, thin bone that is prone to fractures due to its location and the forces exerted on it during a fall.

**Why Each Wrong Option is Incorrect**
**Option A:** Malunion is a possible complication of clavicle fractures, but it is not a characteristic of the injury itself. Malunion occurs when the bone heals in an abnormal position.

**Option B:** The most common site of clavicle fractures is actually the middle third, not the medial 1/3rd and 2/3rd. The middle third is more susceptible to fractures due to its location and the forces exerted on it during a fall.

**Option C:** Comminuted fractures can occur in any bone, including the clavicle, but they are not the most common type of clavicle fracture. Comminuted fractures involve multiple fragments of bone.

**Clinical Pearl / High-Yield Fact**
A mnemonic to remember the common sites of clavicle fractures is "MIDDLE": Middle third (most common), Medial third (less common), and Lateral third (least common).

**Correct Answer: D. Due to fall on outstretched hand**