The correct answer is C — Strong authentication.

According to WGU Cybersecurity Architecture and Engineering (KFO1 / D488) materials, PCI DSS compliance requires strong access controls, including strong authentication mechanisms, especially when accessing environments containing cardholder data. SSH access must be protected with methods such as multi-factor authentication or strong, complex credentials to ensure that only authorized users gain access.

Patch management (A) maintains system security but is not specifically about authentication. Network segmentation (B) limits data exposure but does not directly relate to authentication. Vulnerability analysis (D) identifies weaknesses but does not address the need for strong authentication when connecting to sensitive environments.

Reference Extract from Study Guide:

"Strong authentication mechanisms are crucial to protect access to environments that store, process, or transmit cardholder data, in compliance with PCI DSS standards."

— WGU Cybersecurity Architecture and Engineering (KFO1 / D488), Regulatory Compliance and Access Control

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