**Core Concept**
Delusions are fixed, false beliefs that are not amenable to change in light of conflicting evidence. They are a hallmark symptom of psychotic disorders, including schizophrenia, and can occur in other conditions such as severe depression and mania.

**Why the Correct Answer is Right**
Anxiety disorders, including anxiety itself, do not typically feature delusions as a primary symptom. While anxiety can be a comorbid condition in patients with psychotic disorders, it does not meet the diagnostic criteria for a psychotic disorder and is not characterized by the presence of delusions. Anxiety disorders are primarily marked by excessive fear, worry, or anxiety that interferes with functioning, but not by the presence of delusional thinking.

**Why Each Wrong Option is Incorrect**
**Option A:** Depression can feature delusional thinking, particularly in severe cases, where patients may experience delusions of guilt, worthlessness, or impending doom.
**Option C:** Schizophrenia is characterized by the presence of delusions, which can be of various types, including persecutory, grandiose, or somatic.
**Option D:** Mania, particularly in bipolar disorder, can feature psychotic symptoms, including delusions, which can be grandiose or persecutory in nature.

**Clinical Pearl / High-Yield Fact**
When evaluating patients for psychotic symptoms, it is essential to consider the presence of other symptoms, such as hallucinations, disorganized thinking, and negative symptoms, to establish a diagnosis of a psychotic disorder. Anxiety disorders, while common, do not typically feature delusions as a primary symptom.

✓ Correct Answer: B. Anxiety