The phase of schizophrenia marked by a slow, steady deterioration and gradual decline in function before clear-cut psychotic behaviors emerge is called the phase.

The correct answer is the prodromal phase.

Explanation:

Schizophrenia is a mental disorder that changes or affects how an individual thinks, behaves or feels. This individual seems like they have no touch with reality.

The prodromal phase is the initial phase of the schizophrenia which is characterized by anxiety, mood swings, sleeping disturbance, depression,  anger, and suicidal thoughts are reported as part of prodromal symptoms. He might have a gradual decline and steady deterioration in behavior.

Thus, the correct answer is the prodromal phase.

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