**Core Concept**
Cozen's test is a clinical examination technique used to diagnose lateral epicondylitis, also known as tennis elbow. This condition involves inflammation of the tendons that attach to the lateral epicondyle of the humerus, leading to pain and tenderness in the area. The test relies on the principle of resisted wrist extension to assess the integrity of the common extensor tendon.

**Why the Correct Answer is Right**
Cozen's test involves the patient making a fist and holding it with the wrist extended, then the examiner applies resistance to the wrist while the patient tries to extend it against the resistance. This movement specifically tests the common extensor tendon, which is responsible for wrist extension and is commonly affected in lateral epicondylitis. The test is positive if the patient experiences pain or tenderness in the lateral epicondyle area.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Cozen's test is not used to diagnose radial tunnel syndrome, which involves compression of the radial nerve.
**Option B:** This option is incorrect because Cozen's test is not used to diagnose medial epicondylitis, which affects the medial aspect of the elbow and is also known as golfer's elbow.
**Option C:** This option is incorrect because Cozen's test is not used to diagnose olecranon bursitis, which involves inflammation of the bursa at the back of the elbow.

**Clinical Pearl / High-Yield Fact**
Cozen's test is a useful clinical tool for diagnosing lateral epicondylitis, but it's essential to consider other factors such as patient history and physical examination findings to confirm the diagnosis.

**Correct Answer:** C.