During surgery for aoic arch aneurysm under deep hypothermic circulatory arrest, which of the following anesthetic agent administered prior to circulatory arrest that also provides cerebral protection?

B i.e. Thiopentone Sodium Surgery from aoic arch aneurysm carries a great risk for hypoxic injury of brain; so surgery is performed using deep hypothermiaQ & circulatory arrest method (based on principle that brain can tolerate circulatory arrest for periods of upto 45 minutes if temperature is lowered to 15-17deg C during surgery. During this process a cerebroprotective agent4 is needed which lowers the metabolic demands of brain by eliminating metabolic cost of electrical activity and protect brain from hypoxia by reducing cerebral edema & free radicle formation. Thiopentone (Barbiturate)Q is definitely a cerebroprotective drugQ Other probable drugs are Etomidate, Propofol, Isoflurane, Ketamine