Final answer:
Medical doctors hold exclusive and unrestricted prescribing authority in every state, as states have the power to grant and regulate professional licenses.
Step-by-step explanation:
Medical doctors have exclusive, unrestricted prescribing authority in every state. This authority is granted to them by state governments, which rely on their reserved powers to regulate health, public safety, moral behavior, and general welfare. Each state is in charge of licensing professionals such as medical doctors, and the scope of practice, including prescription privileges, is defined at the state level.