**Core Concept**
Delusional disorder is a psychiatric condition characterized by the presence of one or more non-bizarre delusions that last for at least a month. The delusions are not part of a schizophrenia spectrum disorder and do not cause significant distress or impairment in social, occupational, or other areas of functioning.

**Why the Correct Answer is Right**
Delusional disorder typically does not involve hallucinations, which are a common feature in schizophrenia. The delusions in delusional disorder are usually fixed and not easily changeable, even when confronted with evidence to the contrary. The disorder is often associated with a normal or near-normal level of cognitive functioning and no significant impairment in social or occupational functioning.

**Why Each Wrong Option is Incorrect**
**Option A:** This statement is incorrect because delusional disorder may involve significant distress or impairment in social, occupational, or other areas of functioning, although this is not a necessary criterion for diagnosis.

**Option B:** This statement is incorrect because delusional disorder often involves significant impairment in social, occupational, or other areas of functioning, particularly if the delusions are related to relationships or work.

**Option C:** This statement is incorrect because delusional disorder typically does not involve hallucinations, which are a common feature in schizophrenia.

**Clinical Pearl / High-Yield Fact**
Delusional disorder is often associated with a normal or near-normal level of cognitive functioning, which can make it difficult to diagnose and distinguish from other psychiatric conditions.

**Correct Answer: C. Delusional disorder typically does not involve hallucinations.**