The correct answer is C - Least privilege.
According to the WGU Cybersecurity Architecture and Engineering (KFO1 / D488) course material, the principle of least privilege ensures that users are granted only the minimum level of access required to perform their job functions. In this case, if the insider only had access to resources necessary for their user role, they would not have been able to access sensitive administrative information.
Password complexity (A) strengthens account security but does not prevent excessive access. Separation of duties (B) divides critical tasks but is not solely about limiting access. Job rotation (D) moves employees between roles but is not an access control measure.
Reference Extract from Study Guide:
"The principle of least privilege requires limiting user access rights to the minimum necessary to perform their tasks, reducing the risk of insider threats and unauthorized access to sensitive information."
- WGU Cybersecurity Architecture and Engineering (KFO1 / D488), Access Control Principles