Which of the following agents is not used to provide induced hypotension during surgery?

Mephenteramine is an indirect acting sympathomimetic drug. It is used to treat the hypotension induced by ganglion blockers or spinal anaesthesia. Therefore not used to induce hypotension. Esmolol, hydralazine and sodium nitroprusside are commonly used agents to provide induced hypotension during surgery. Cerebral blood flow remains constant in an intact brain over a mean aerial blood pressure range 50-150mmHg. Induced hypotension is employed to reduce blood loss. Ref: Textbook of Neurosurgery By Prakash Narain Tandon, Volume 1, Page 927; Medical Toxicology By Richard C. Da, 3rd Edition, Page 551.