Prescription drugs may lead to dependence when used for which purpose?

The correct answer focuses on the fact that using prescription drugs for non-medical reasons increases the risk of developing dependence. When individuals take medications without a legitimate medical need—such as to achieve a high, manage stress, or enhance performance—they are engaging in misuse. This type of use can lead to tolerance, where more of the drug is needed to achieve the same effect, and ultimately, dependence, where the individual feels unable to function normally without the drug.

In contrast, using prescription drugs according to a doctor's instructions, such as for a legitimate medical condition, generally aims to manage health issues and minimizes the risk of developing dependence. Likewise, activities during controlled studies typically involve strict supervision and protocols that monitor usage and reduce the risk of misuse. Therefore, it's the non-medical use that presents significant dangers regarding dependence.