**Core Concept**
The presence of depressive symptoms in patients with schizophrenia can be a good prognostic factor, indicating a better response to treatment and a more favorable outcome. This is because depressive symptoms often reflect a more intact emotional and cognitive functioning, which is associated with a better prognosis.

**Why the Correct Answer is Right**
The presence of depression in schizophrenia is often seen as a positive prognostic sign because it suggests that the patient's emotional and cognitive functioning is not completely impaired. Depressive symptoms in schizophrenia can be a manifestation of a more nuanced psychiatric presentation, where the patient is able to experience a range of emotions, including sadness and hopelessness. This is in contrast to patients with schizophrenia who exhibit blunted affect, which is a negative symptom that can indicate a poorer prognosis. Additionally, the presence of depression can make patients more adherent to treatment and more responsive to psychosocial interventions.

**Why Each Wrong Option is Incorrect**
**Option A:** Blunted affect is a negative symptom of schizophrenia, characterized by a reduction in emotional expression and a lack of responsiveness to emotional stimuli. It is associated with a poorer prognosis and a more severe course of the illness.
**Option B:** Early onset of schizophrenia is often associated with a poorer prognosis, as it can indicate a more severe and chronic form of the illness. Early onset is often characterized by a more rapid progression of symptoms and a greater impairment in social and cognitive functioning.
**Option D:** Male sex is not a good prognostic factor for schizophrenia. In fact, studies have shown that females with schizophrenia often have a better prognosis and a more favorable outcome than males.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the presence of depressive symptoms in schizophrenia is not a guarantee of a good prognosis, and each patient should be evaluated individually. However, in general, depressive symptoms can be a positive prognostic sign and should be treated as such.

✓ Correct Answer: C. Presence of depression