Which compound is derived from the opium poppy?

The compound derived from the opium poppy is codeine. This natural alkaloid is one of the primary opioids extracted from the sap of the opium poppy (Papaver somniferum) and is well-known for its analgesic (pain-relieving) properties. Codeine is often used in medical settings to treat mild to moderate pain and can also act as a cough suppressant.

In contrast, the other compounds listed have different sources and uses. Atropine, for instance, is derived from plants in the nightshade family, particularly Atropa belladonna, and is commonly used for its anticholinergic properties in medicine. Camptothecine is a compound sourced from the bark of the Camptotheca acuminata tree and has significant applications in cancer therapy due to its role in inhibiting DNA replication. Reserpine is derived from the Rauwolfia serpentina plant and is used primarily in the treatment of hypertension and certain psychotic disorders.

This distinction highlights why codeine is specifically associated with the opium poppy, making it the correct choice in the context of the question.