The IT security team is implementing security best practices to reduce the risk of unauthorized access of drives and folders by internal employees. Which method best ensures compliance with this requirement?

A$.$Implement intrusion detection systems to monitor and identify potential security breaches

B$.$Implement a firewall to protect the company's network from external threats

C$.$Enforce mandatory password changes every month to enhance password security

D$.$The principle of least privilege to grant employees the minimum needed access based on job roles