**Core Concept**
The phenomenon described is a classic presentation of a psychiatric disorder characterized by a disconnection from one's self, feelings of strangeness, and anxiety. This is often associated with a disruption in normal thought patterns and ego boundaries.

**Why the Correct Answer is Right**
The correct answer refers to a feeling of detachment from oneself, which is a hallmark symptom of depersonalization disorder. This condition is characterized by a feeling of being an outside observer of oneself, as if one is watching oneself from outside the body. The disconnection from one's thoughts, feelings, and bodily sensations can lead to feelings of anxiety, tension, and distress. Depersonalization is often seen as a coping mechanism in response to trauma, stress, or anxiety.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because derealization is a related but distinct phenomenon, where the individual feels as if the world around them is unreal or dream-like.

**Option B:** This option is incorrect because depersonalization disorder is not the same as dissociative amnesia, which involves a loss of memory or identity.

**Option C:** This option is incorrect because depersonalization disorder is not the same as schizotypal personality disorder, which involves eccentric behavior and a distorted sense of self.

**Clinical Pearl / High-Yield Fact**
Depersonalization disorder often co-occurs with other anxiety disorders and trauma. Recognizing the distinct symptoms of depersonalization can help clinicians provide accurate diagnoses and effective treatment.

**Correct Answer:** D. Depersonalization disorder.