**Core Concept**
The spinal cord is a vital part of the central nervous system, extending from the base of the brain down to the lower back. Its anatomy is crucial for understanding various neurological conditions and injuries.

**Why the Correct Answer is Right**
The spinal cord in adults indeed terminates at the level of the lower border of the first lumbar vertebra (L1), which is a well-established anatomical landmark. Additionally, in newborns, the spinal cord may extend up to the level of the third lumbar vertebra (L3) due to the relatively longer length of the vertebral column compared to the spinal cord. Furthermore, the cauda equina is a collection of nerve roots that arise from the lower end of the spinal cord and extend down to the coccyx, providing a vital nerve supply to the lower limb.

**Why Each Wrong Option is Incorrect**
**Option A:** This statement is partially incorrect because the spinal cord actually ends at the level of the lower border of L1, not the vertebral body. The vertebral body and the disc are distinct anatomical structures.
**Option B:** This statement is partially incorrect because, although the spinal cord may extend up to L3 in newborns, it is not a universal characteristic and may vary depending on the individual.
**Option C:** This statement is partially incorrect because the cauda equina is not limited to the lumbar vertebrae; it extends down to the coccyx.

**Clinical Pearl / High-Yield Fact**
The spinal cord's termination at L1 is a crucial landmark for understanding various neurological conditions, such as spinal cord injuries, syringomyelia, and spinal stenosis. It is essential to remember that the spinal cord's anatomy can be affected by various factors, including age, disease, and trauma.

**✓ Correct Answer: D. All**