Which drug is an effective painkiller for patients who have undergone surgery?

Morphine

The correct answer is Option (3) → Morphine

Opioids are the drugs, which bind to specific opioid receptors present in our central nervous system and gastrointestinal tract. Heroin , commonly called smack is chemically diacetylmorphine which is a white, odourless, bitter crystalline compound. This is obtained by acetylation of morphine. Heroin is derived from morphine, which is a naturally occurring alkaloid found in the latex sap of the opium poppy plant, Papaver somniferum. The opium poppy plant has been cultivated for centuries for its medicinal properties. Morphine is a very effective sedative and painkiller, and is very useful in patients who have undergone surgery.