Which substance is considered a Narcotic Drug because it is derived from coca leaves?

Cocaine is considered a narcotic drug because it is directly derived from coca leaves, which are the source of its active compound. This classification is rooted in cocaine's effects on the central nervous system, where it acts as a powerful stimulant and can lead to significant dependence and addiction. Its legal status and regulation stem from the potential for abuse and the serious health risks it poses.

The other substances listed do not fit this classification. Marihuana, while it has psychoactive effects, comes from the cannabis plant and is processed differently, leading it to be classified as a cannabinoid rather than a narcotic. Hemp is also a cannabis plant but is specifically cultivated for non-psychoactive uses, primarily for fiber and seeds, and is not considered a narcotic. Oil cake, often a byproduct of oil extraction from various seeds, does not possess narcotic properties. This context highlights why cocaine is the designated narcotic drug in this question.