**Core Concept:** Fractures in elderly individuals are often due to low-energy trauma, and the outstretched hand mechanism is a common mechanism of injury.

**Why the Correct Answer is Right:** The correct answer is **D** - Colles' fracture. Colles' fracture occurs when an elderly individual falls onto their outstretched hand, causing the forearm to bend backwards and forcefully. The radial head dislocates from the radial neck, leading to an unstable fracture pattern.

**Why Each Wrong Option is Incorrect:**

A. Salter-Harris type I fracture (a physeal fracture) is not the correct answer because it usually affects the distal end of the radius in children, not elderly individuals.

B. Pilon fracture (a high-energy ankle fracture) is incorrect because it involves the tibia or fibula, not the radius.

C. Femoral neck fracture (a high-energy fracture) is wrong because it occurs in the proximal femur, not the radius.

**Clinical Pearl:** The fall on outstretched hand mechanism highlights the importance of assessing elderly patients' mobility, balance, and home environment for fall prevention strategies.

**Correct Answer:** Colles' fracture (D) is the commonest fracture in the elderly population due to this mechanism, whereas Salter-Harris type I (A), Pilon fracture (B), and femoral neck fracture (C) are not common in this group.