A 20-year-old boy complains of hearing of voices and aggressive behavior for last 2 days. He had fever before the onset of these symptoms. The family members report that he has been muttering to self and gesticulating as if he is talking to someone. There is no history of any past psychiatric illness. The likely diagnosis is:

**Core Concept**
Schizophrenia is a chronic and severe mental disorder characterized by distortions in thinking, perception, emotions, language, sense of self, and behavior. Common symptoms include hallucinations, delusions, disorganized thinking, and negative symptoms such as apathy or lack of emotion.

**Why the Correct Answer is Right**
The patient's symptoms of hearing voices (auditory hallucinations) and aggressive behavior, along with a recent onset and no past psychiatric history, are suggestive of a psychotic disorder. The presence of fever before the onset of symptoms may indicate an organic cause for the psychosis, such as a viral infection or autoimmune disorder. The patient's gesticulation as if talking to someone may be indicative of command hallucinations, a common type of auditory hallucination in schizophrenia.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the symptoms described. While it may be a consideration in some cases of psychosis, it is not the most likely diagnosis based on the information provided.

**Option B:** This option is not consistent with the patient's symptoms. While mood disorders can present with psychotic symptoms, the absence of a clear mood disturbance or past psychiatric history makes this option less likely.

**Option C:** This option is not supported by the patient's symptoms. While anxiety disorders can present with a range of symptoms, the presence of auditory hallucinations and aggressive behavior is not typical of anxiety disorders.

**Clinical Pearl / High-Yield Fact**
In cases of acute psychosis, particularly in young adults with no past psychiatric history, it is essential to consider an organic cause such as a viral infection or autoimmune disorder, and to rule out other medical conditions that may be contributing to the patient's symptoms.

**Correct Answer: C. Schizophrenia**

✓ Correct Answer: B. Acute psychosis