**Core Concept**
Brown-Séquard syndrome is a neurological condition characterized by hemisection of the spinal cord, resulting in ipsilateral weakness and loss of proprioception, with contralateral loss of temperature and pain sensation below the level of the lesion.

**Why the Correct Answer is Right**
The syndrome occurs due to damage to one half of the spinal cord, which disrupts the crossing of sensory and motor tracts at the level of the spinal cord. The corticospinal tracts, which carry motor signals, descend in the lateral column of the spinal cord and cross over to the contralateral side at the level of the medulla, resulting in ipsilateral weakness. The posterior columns of the spinal cord, which carry proprioceptive and vibration signals, are located in the dorsal (back) part of the spinal cord and are affected on the same side as the lesion, resulting in loss of proprioception. In contrast, the spinothalamic tracts, which carry pain and temperature signals, are located in the lateral part of the spinal cord and cross over to the contralateral side shortly after entering the spinal cord, resulting in loss of pain and temperature sensation on the opposite side of the lesion.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to Brown-Séquard syndrome, which is a specific neurological condition resulting from hemisection of the spinal cord.
**Option B:** This option may be related to other neurological conditions, such as syringomyelia, which can cause loss of proprioception and temperature sensation, but is not characteristic of Brown-Séquard syndrome.

**Clinical Pearl / High-Yield Fact**
Brown-Séquard syndrome is often caused by traumatic injuries to the spinal cord, such as falls or motor vehicle accidents, and can also be caused by penetrating injuries, such as gunshots or stabbings.

**Correct Answer: D. Brown-Séquard syndrome is characterized by ipsilateral weakness and loss of proprioception, with contralateral loss of temperature and pain sensation below the level of the lesion.**