This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anesthesia, Subject name: Pharmacology
[{'content': 'Anesthetic not painful on Intravenous administration is \nSelect and explain. \nA. Methohexital, B. Etomidate, C. Propofol, D. Ketamine', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ketamine:- * Ketamine on intravenous administration is absolutely devoid of pain at injection site. * Ketamine is a NMDA antagonist intravenous general anesthetic agent - that induces a characteristic cataleptic state called "Dissociative Anesthesia" - a state of induced dissociation from onself and surrounding. * Dissociative anesthesia is due to selective interruption of association pathways in the neocoex and thalamus --> characteristic somato-sensory blockade, a combination of Catalepsy +Catatonia+ Analgesia+ Amnesia (without complete loss of consciousness like other general anesthetics) Ref:- Goodman & Gilman Pharmacological Basis of Therapeutics 13th Ed; Pg num:- 391', 'role': 'assistant'}]