**Core Concept**
Conus medullaris syndrome is a clinical condition resulting from damage to the conus medullaris, the lowest part of the spinal cord, which affects the lower sacral and coccygeal nerve roots (S2-S5). This damage leads to a range of neurological deficits due to disruption of the descending and ascending tracts in the spinal cord.

**Why the Correct Answer is Right**
The clinical features of conus medullaris syndrome include lower motor neuron signs such as flaccid paralysis, loss of reflexes, and sensory loss below the level of injury. Additionally, autonomic dysfunction may manifest as urinary retention, constipation, and impotence due to the involvement of the sympathetic and parasympathetic pathways. These symptoms are a result of the damage to the conus medullaris and the subsequent disruption of the descending and ascending tracts.

**Why Each Wrong Option is Incorrect**
**Option B:** This option is incorrect because it is not a characteristic feature of conus medullaris syndrome. Conus medullaris syndrome typically presents with flaccid paralysis rather than spasticity, which is more commonly associated with upper motor neuron lesions.

**Option C:** This option is incorrect because it is not a specific clinical feature of conus medullaris syndrome. While sensory loss may occur in conus medullaris syndrome, it is typically limited to the perineal area and the lower sacral dermatomes (S2-S5).

**Option D:** This option is incorrect because it is not a characteristic feature of conus medullaris syndrome. Conus medullaris syndrome typically presents with urinary retention rather than incontinence, due to the disruption of the autonomic pathways controlling the bladder.

**Clinical Pearl / High-Yield Fact**
One key point to remember is that conus medullaris syndrome typically presents with flaccid paralysis and loss of reflexes below the level of injury, rather than spasticity. This is in contrast to upper motor neuron lesions, which typically present with spasticity and hyperreflexia.

**Correct Answer: B.**