**Core Concept**
Schizophrenia is a chronic and severe mental disorder characterized by disruptions in thought processes, perceptions, emotional responsiveness, and social interactions. The disorder involves a complex interplay between genetic, environmental, and neurochemical factors.

**Why the Correct Answer is Right**
The symptoms of schizophrenia are typically classified into positive and negative symptoms. Positive symptoms include hallucinations, delusions, disorganized thinking, and bizarre behavior, which are thought to result from an overactive dopamine system in the brain. Negative symptoms, such as apathy, anhedonia, and social withdrawal, are believed to be related to an underactive dopamine system. The correct answer should be a characteristic that is not typically associated with schizophrenia.

**Why Each Wrong Option is Incorrect**
**Option A:** Hallucinations are a common positive symptom of schizophrenia, often involving auditory or visual disturbances. Incorrect because this is a characteristic of schizophrenia.
**Option B:** Disorganized thinking and speech are also typical of schizophrenia, often manifesting as incoherent or irrelevant conversations. Incorrect because this is a characteristic of schizophrenia.
**Option C:** Social withdrawal is a negative symptom of schizophrenia, often leading to impaired interpersonal relationships. Incorrect because this is a characteristic of schizophrenia.

**Clinical Pearl / High-Yield Fact**
Schizophrenia is often associated with a higher risk of comorbid medical conditions, including cardiovascular disease, diabetes, and obesity, particularly due to the side effects of antipsychotic medications.

**Correct Answer: C. Social withdrawal is a characteristic of schizophrenia.**