**Core Concept**
The patient's condition, characterized by amnesia and a lack of knowledge about their past life, suggests a disruption in their memory and identity. This could be due to a neurological disorder, psychological trauma, or a medical condition affecting the brain.

**Why the Correct Answer is Right**
The patient's symptoms are consistent with Dissociative Amnesia, a condition where a person is unable to recall important information about their past, often due to a traumatic event. This condition is characterized by the inability to recall memories from a specific time period, which can be due to a psychological response to trauma, stress, or anxiety. Dissociative Amnesia is often associated with Dissociative Identity Disorder (DID), where a person experiences multiple identities or alters, each with their own memories and experiences.

**Why Each Wrong Option is Incorrect**
**Option A:** Korsakoff's Syndrome is a neurological disorder caused by thiamine deficiency, typically seen in chronic alcoholics. It is characterized by memory loss, confusion, and difficulty with learning new information, but it does not typically involve amnesia about one's past life.

**Option B:** Post-Traumatic Amnesia (PTA) is a condition where a person is unable to recall events that occurred after a traumatic event, but they may still have memories of their past life. PTA is often seen in individuals who have experienced a head injury or a traumatic event.

**Option C:** Alzheimer's Disease is a progressive neurological disorder that affects memory, thinking, and behavior. It is characterized by the degeneration of brain cells, leading to memory loss and cognitive decline, but it typically affects older adults and does not involve sudden amnesia about one's past life.

**Option D:** Psychogenic Amnesia is a condition where a person loses their memories due to psychological trauma or stress. However, it is less common than Dissociative Amnesia and typically involves a more gradual loss of memories.

**Clinical Pearl / High-Yield Fact**
Dissociative Amnesia can be a defense mechanism to cope with traumatic events, and it is essential to approach patients with empathy and understanding to help them recover their memories and work through their trauma.

**Correct Answer: D. Dissociative Amnesia.**