A 19 year old boy suffering from chronic schizophrenia is put on haloperidol in the dose of 20 mg/day.A week after the initiation of medication the patient shows be restlessness, fidgety, irritability and can not sit still at one place.The most appropriate treatment strategy is -

• A. Adding another antipsychotic drug
• B. Adding of betablocker
• C. Increase in the dose of the haloperidol
• D. Addition of anticholinergic drug