Answer:
B. from a pharmacy.
Step-by-step explanation:
Prescription drugs or prescription medicines are the pharmaceutical drugs that only can be sold with a medical prescription, otherwise, they can't be delivered to costumers. So, in this case, we are talking about medicines that actually have a prescription, the legal way to obtaining them is through a pharmacy.
The main reason for this is substance control, which is regulation from the government of certain medicine's production, possession, manufacture and selling.