Final answer:
A pharmacist is required to assess the appropriateness of therapy before selling medications that fall under Schedule II, as these substances have a high potential for abuse and dependence.
Step-by-step explanation:
The schedule that requires a pharmacist to assess the appropriateness of therapy before selling is Schedule II. Pharmaceutical drugs are categorized into different schedules based on their potential for abuse, safety, and the need for oversight by healthcare professionals. Schedule II medications are controlled substances that have a high potential for abuse which may lead to severe psychological or physical dependence. These medications, therefore, require a healthcare professional's assessment to ensure that they are used appropriately and safely.