**Core Concept**
Spinal tuberculosis (TB) is a type of extrapulmonary tuberculosis that affects the spine, leading to destruction of the vertebral bodies and potentially causing neurological deficits. The investigation of choice for spinal TB should ideally provide a comprehensive assessment of the spinal column, adjacent soft tissues, and possible neurological involvement.

**Why the Correct Answer is Right**
Magnetic Resonance Imaging (MRI) is the investigation of choice for spinal TB due to its excellent soft tissue contrast and ability to visualize the spinal cord, vertebral bodies, and intervertebral discs. MRI can detect early changes in the spine, such as vertebral body collapse, disc space narrowing, and epidural abscess formation. Additionally, MRI can assess the involvement of adjacent soft tissues, including paraspinal muscles and ligaments, and evaluate the extent of neurological compression.

**Why Each Wrong Option is Incorrect**
* **Option A:** X-rays are not sufficient for diagnosing spinal TB, as they may not detect early changes in the spine and can be normal in the early stages of the disease.
* **Option B:** CT scans can provide detailed images of the bony structures, but they may not be as sensitive as MRI in detecting soft tissue involvement and early changes in the spine.
* **Option C:** Plain radiographs may show vertebral body collapse and disc space narrowing, but they may not provide a comprehensive assessment of the spinal column and adjacent soft tissues.

**Clinical Pearl / High-Yield Fact**
MRI is essential in the evaluation of spinal TB, as it can detect early changes in the spine and adjacent soft tissues, allowing for prompt initiation of treatment and potentially preventing long-term neurological damage.

**Correct Answer:** C.