A patient has been taking a D2 blocking agent and has developed muscle rigidity and high fever. What medication would the patient mostly receive for these symptoms?

A. Amantadine: Amantadine is primarily used for mild Parkinsonism and as an antiviral. While it has dopaminergic activity, it is generally insufficient for treating the severe muscle rigidity and hyperthermia seen in neuroleptic malignant syndrome (NMS). B. Dantrolene: Dantrolene is a muscle relaxant that directly acts on skeletal muscle to reduce rigidity and heat production. It is the mainstay treatment for NMS, helping to alleviate life-threatening hyperthermia and muscle stiffness caused by D2 receptor blockade. C. Benztropine: Benztropine is an anticholinergic used for extrapyramidal symptoms such as Parkinsonism and dystonia. It does not adequately address the hyperthermia or severe muscle rigidity of NMS. D. Diphenhydramine: Diphenhydramine can relieve mild dystonic reactions due to its anticholinergic properties, but it is not sufficient for the systemic and life-threatening manifestations of NMS such as high fever and profound rigidity.