**Core Concept**
The long thoracic nerve is a motor nerve that innervates the serratus anterior muscle, playing a crucial role in shoulder stability and movement. Testing its integrity is essential for diagnosing nerve injuries or damage.

**Why the Correct Answer is Right**
To test the long thoracic nerve, the physician performs the "Serratus Anterior Test" or "Wing Test". This involves asking the patient to place their hand on their hip and then to push their hand against an immovable object, such as a wall. The examiner observes the patient's scapula for winging, which is a sign of serratus anterior muscle weakness due to long thoracic nerve damage. The test relies on the patient's ability to contract the serratus anterior muscle, which is innervated by the long thoracic nerve.

**Why Each Wrong Option is Incorrect**
**Option A:** The "Belly Press Test" is used to assess the rectus abdominis muscle, not the long thoracic nerve.
**Option B:** The "Scapular Squeeze Test" is used to assess the trapezius muscle, not the long thoracic nerve.
**Option C:** The "Shoulder Abduction Test" is used to assess the supraspinatus and deltoid muscles, not the long thoracic nerve.

**Clinical Pearl / High-Yield Fact**
The long thoracic nerve can be compressed or damaged due to various causes, including trauma, surgical procedures, or even repetitive strain from overhead throwing or lifting. Recognizing the signs of long thoracic nerve damage, such as scapular winging, is crucial for prompt diagnosis and treatment.

**Correct Answer:** C.