**Core Concept**
De Clerambault's syndrome is a psychiatric condition characterized by a delusional belief that another person, usually someone of higher social status or a celebrity, is in love with the individual. This delusion is a type of delusional disorder, which involves a persistent and fixed false belief that is not amenable to change in light of conflicting evidence.

**Why the Correct Answer is Right**
De Clerambault's syndrome is named after the French psychiatrist Gaëtan Gatian de Clérambault, who first described this condition in the early 20th century. The key feature of this syndrome is the patient's conviction that another person is passionately in love with them, often accompanied by a sense of grandeur and a distorted perception of reality. This delusional thinking can be resistant to treatment and may lead to significant distress and impairment in social and occupational functioning.

**Why Each Wrong Option is Incorrect**
**Option A:** Ekbom's syndrome, also known as delusional parasitosis, is a different psychiatric condition characterized by a delusional belief that one's skin is infested with parasites. This condition is distinct from De Clerambault's syndrome in terms of its symptomatology and underlying pathology.
**Option C:** Querulous paranoia is a type of paranoid personality disorder characterized by a pervasive and excessive preoccupation with perceived slights and injustices. While it involves delusional thinking, it is not specifically related to a delusional belief in being loved by another person.
**Option D:** Othello syndrome, also known as morbid jealousy, is a psychiatric condition characterized by an excessive and irrational preoccupation with one's partner's alleged infidelity. While it involves delusional thinking, it is distinct from De Clerambault's syndrome in terms of its symptomatology and underlying pathology.

**Clinical Pearl / High-Yield Fact**
De Clerambault's syndrome is often associated with a history of trauma, abuse, or neglect, and may be more common in women than men. It is essential for clinicians to recognize this condition and provide supportive therapy to help manage the patient's delusional thinking and associated distress.

**✓ Correct Answer: B. De Clerambault's syndrome**