**Core Concept**
A conus lesion refers to a type of spinal cord injury that affects the conus medullaris, the lowermost part of the spinal cord. This region is responsible for controlling the function of the lower limbs, bladder, and bowel. The injury can result in a range of symptoms, including sensory loss, motor weakness, and autonomic dysfunction.

**Why the Correct Answer is Right**
In a conus lesion, the damage to the spinal cord disrupts the normal functioning of the autonomic nervous system, leading to impaired bladder control and urinary retention. This is due to the involvement of the sacral spinal cord segments (S2-S5), which control the parasympathetic outflow to the bladder. As a result, patients with conus lesions often experience urinary incontinence, retention, or overflow incontinence.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because a conus lesion is not primarily characterized by upper motor neuron signs, which are more commonly associated with injuries to the cervical or thoracic spinal cord.
* **Option B:** This option is incorrect because a conus lesion does not typically result in the complete loss of bladder control, as the patient may still retain some residual bladder function.
* **Option C:** This option is incorrect because a conus lesion is not primarily associated with the loss of pain and temperature sensation, as the patient may still retain some sensation in the lower limbs.

**Clinical Pearl / High-Yield Fact**
A key feature of conus lesions is the presence of a "saddle" anesthesia, which refers to the loss of sensation in the perineum, genitalia, and anus. This is due to the involvement of the sacral spinal cord segments, which are responsible for transmitting sensory information from these areas.

**Correct Answer:** A.