**Core Concept**
Supination is a complex movement of the forearm and wrist that involves the rotation of the radius bone around the ulna, resulting in the palm facing upwards. This movement is essential for various daily activities, including writing and using tools.

**Why the Correct Answer is Right**
Supination occurs primarily at the radioulnar joint, specifically at the proximal radioulnar joint, where the head of the radius bone articulates with the radial notch of the ulna. During supination, the radius bone rotates around the ulna, allowing the forearm to rotate from a pronated position (palm facing downwards) to a supinated position (palm facing upwards). This movement is facilitated by the annular ligament, which holds the head of the radius bone in place.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because supination primarily occurs at the radioulnar joint, not the elbow joint.
* **Option B:** This option is incorrect because rotation of the scapula is not directly involved in the movement of supination.
* **Option C:** This option is incorrect because flexion and extension of the elbow joint are not the primary movements involved in supination.

**Clinical Pearl / High-Yield Fact**
The radioulnar joint is a unique joint that allows for rotational movement, and its stability is essential for various daily activities. The annular ligament plays a crucial role in maintaining the stability of the radioulnar joint.

**Correct Answer:** C.