The correct option is
A Morphine
Morphine is a natural opiate. Opiates are considered as king of narcotics. They are derived from opium, the dried latex of unripen capsular fruits of poppy plant Papaver somniferum. They have analgesic, sedative and narcotic effects. Morphine is a depressant of central nervous system. It is a strong sedative and pain killer and given to the patients who have undergone surgery because it reduces pain and induces sleep.
So, the correct answer is 'Morphine'.