Which schedule is defined by having the least potential for abuse and includes codeine cough syrup?

The correct schedule characterized by having the least potential for abuse and including codeine cough syrup is Schedule V.

Schedule V substances are those that have a lower potential for abuse relative to substances in higher schedules (I through IV) and are typically used for medicinal purposes. Codeine cough syrup falls into this category because it contains small amounts of codeine, which is effective in treating cough but does not produce strong euphoric effects when taken as prescribed. The regulation of these substances reflects their relatively mild potential for dependency compared to more controlled medications.

Drugs in higher schedules, such as Schedule I, are considered to have a high potential for abuse with no accepted medical use, while Schedule II substances have a higher abuse potential and may lead to severe dependence. Schedule III substances have a moderate potential for abuse but are more strictly regulated than Schedule V drugs, making Schedule V the most lenient in terms of regulatory restrictions. Thus, the classification of codeine cough syrup in Schedule V appropriately aligns with its lower potential for misuse.