Final answer:
Controlled substances must be stored in a double-locked cabinet to ensure security and comply with regulatory requirements, thus preventing unauthorized access and potential abuse.
Step-by-step explanation:
The question pertains to the proper storage requirements of controlled substances in a healthcare setting. Controlled substances must be stored in a secure manner to prevent unauthorized access and potential abuse. The correct answer to the question is b. in a double-locked cabinet. This means that the controlled substances should be kept in a cabinet that has two locks, ensuring an extra level of security. This is a regulatory requirement in many jurisdictions and helps to safeguard the medications by limiting access to only authorized individuals.