**Core Concept**
Korsakoff's syndrome is a neurological disorder characterized by severe memory impairments, particularly anterograde amnesia, and confabulation. It is often associated with chronic alcoholism and thiamine deficiency. The syndrome involves damage to the medial temporal lobe, particularly the hippocampus and surrounding structures.

**Why the Correct Answer is Right**
Korsakoff's syndrome primarily affects memory functions, leading to anterograde amnesia (inability to form new memories) and retrograde amnesia (loss of memories formed before the onset of the disorder). Confabulation, a feature of Korsakoff's syndrome, involves the production of false memories to fill in gaps in memory. However, defective motor skills are not a characteristic feature of Korsakoff's syndrome. The motor symptoms associated with chronic alcoholism, such as ataxia and tremors, are distinct from the cognitive impairments seen in Korsakoff's syndrome.

**Why Each Wrong Option is Incorrect**
**Option A:** Confabulation is indeed a feature of Korsakoff's syndrome, as patients often produce false memories to compensate for their memory deficits.
**Option B:** Retrograde amnesia is also a characteristic feature of Korsakoff's syndrome, as patients may lose memories formed before the onset of the disorder.
**Option C:** Antegrade amnesia is a hallmark of Korsakoff's syndrome, as patients struggle to form new memories.

**Clinical Pearl / High-Yield Fact**
Korsakoff's syndrome is often associated with Wernicke's encephalopathy, a related condition characterized by confusion, ataxia, and ophthalmoplegia. Early recognition and treatment of Wernicke's encephalopathy can prevent the development of Korsakoff's syndrome.

**✓ Correct Answer: D. Defective motor skill. Defective motor skill is not a characteristic feature of Korsakoff's syndrome.**