**Core Concept**
Foville's syndrome is a rare neurological disorder characterized by a constellation of ocular and neurological symptoms resulting from a lesion in the brainstem, specifically the pons. The syndrome involves a combination of ipsilateral (same side) cranial nerve palsies, ataxia, and contralateral (opposite side) hemiparesis.

**Why the Correct Answer is Right**
Foville's syndrome typically presents with a combination of ipsilateral horizontal gaze palsy, contralateral hemiparesis, and ataxia. The horizontal gaze palsy is due to the involvement of the paramedian pontine reticular formation (PPRF) and the abducens nucleus, which are responsible for horizontal eye movements. The contralateral hemiparesis is due to the involvement of the corticospinal tract, which is responsible for motor function.

**Why Each Wrong Option is Incorrect**
**Option A:** Ipsilateral oculomotor nerve palsy is not a characteristic feature of Foville's syndrome.
**Option B:** Contralateral visual field defect is not typically associated with Foville's syndrome.
**Option C:** Nystagmus is not a specific feature of Foville's syndrome, although it can be seen in other brainstem disorders.

**Clinical Pearl / High-Yield Fact**
Foville's syndrome should be distinguished from other brainstem disorders, such as Millard-Gubler syndrome, which involves a lesion in the pons and presents with ipsilateral oculomotor nerve palsy and contralateral hemiparesis.

**Correct Answer: C. Nystagmus is not a specific feature of Foville's syndrome, although it can be seen in other brainstem disorders.**