## Core Concept
The phenomenon described in the question relates to a psychiatric condition where a person mistakenly believes that a familiar person has been replaced by an identical imposter. This condition is a type of delusional disorder.

## Why the Correct Answer is Right
The correct answer, **Capgras syndrome**, also known as imposter syndrome, is a delusional misidentification syndrome. It is characterized by a person's belief that a close relative or friend has been replaced by an identical imposter. This condition often occurs in the context of psychiatric disorders such as schizophrenia, dementia, or severe depression. The delusion is not simply a matter of suspiciousness but a firm, fixed belief that an imposter has taken the place of the familiar person.

## Why Each Wrong Option is Incorrect
- **Option A:** Fregoli syndrome is another type of delusional misidentification syndrome, but it involves the belief that multiple people are actually a single person who changes appearance or is in disguise. This does not match the description provided.
- **Option B:** This option might relate to other psychiatric or psychological conditions but does not specifically describe the phenomenon of a person being replaced by an identical double.
- **Option C:** There might be various syndromes or conditions listed here, but none specifically refer to the belief that a friend or close relative has been replaced by an exact double.

## Clinical Pearl / High-Yield Fact
A key point to remember is that Capgras syndrome is often associated with significant psychiatric or neurological disorders, such as schizophrenia or dementia. Clinicians should be alert to the possibility of underlying serious conditions when encountering patients with such delusions. A useful association to recall is that Capgras syndrome can sometimes be linked with **temporal lobe pathology**.

## Correct Answer: D. Capgras syndrome.