**Core Concept**
A Monteggia fracture is a type of fracture that involves the **ulna** and **radius** bones in the forearm. It is characterized by a fracture of the ulna with a dislocation of the proximal radius. This type of injury is typically caused by a fall onto an outstretched hand.

**Why the Correct Answer is Right**
The correct answer is related to the definition of a Monteggia fracture, which specifically involves the **ulna** and the dislocation of the **radius**. The ulna fracture can be either oblique or transverse, and the dislocation of the radius can be anterior or posterior. The mechanism of injury usually involves a direct blow to the forearm or a fall onto an outstretched hand, leading to the fracture and dislocation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct bones involved in a Monteggia fracture.
**Option B:** This option is also incorrect as it does not accurately describe the injury.
**Option D:** Similarly, this option does not correctly identify the bones involved in a Monteggia fracture.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that a Monteggia fracture involves not just a fracture of the ulna, but also a dislocation of the radius, making it a more complex injury than a simple fracture. The treatment often requires reduction of the dislocation and stabilization of the fracture.

**Correct Answer:** D. Ulna with dislocation of radius.