**Core Concept**
Traumatic paraplegia refers to a type of spinal cord injury that results in the loss of motor and sensory function in the lower extremities. The investigation of choice in such cases is crucial for determining the extent of damage, identifying potential complications, and guiding treatment decisions.

**Why the Correct Answer is Right**
The investigation of choice in traumatic paraplegia is usually an MRI (Magnetic Resonance Imaging) of the spine. This is because MRI provides high-resolution images of the spinal cord, nerve roots, and surrounding soft tissues, allowing for the detection of subtle changes and injuries that may not be visible on other imaging modalities. Specifically, MRI can help identify compression, contusion, or transection of the spinal cord, as well as any associated fractures or dislocations.

**Why Each Wrong Option is Incorrect**
**Option A:** CT (Computed Tomography) scan is not the investigation of choice in traumatic paraplegia because it provides limited information about soft tissue injuries and may not detect subtle changes in the spinal cord.

**Option B:** Plain X-ray is not sufficient for evaluating traumatic paraplegia as it may not detect soft tissue injuries, compression, or other subtle changes in the spinal cord.

**Option C:** Myelography is an older imaging technique that involves injecting a contrast agent into the spinal canal, but it is less sensitive and specific than MRI and carries a higher risk of complications.

**Clinical Pearl / High-Yield Fact**
In cases of traumatic paraplegia, early MRI imaging is crucial for identifying potential complications such as cord compression, hematoma, or abscess formation, which can lead to further neurological deterioration if left untreated.

**Correct Answer: C. MRI of the spine.**