According to Requirement 6, what type of software must organizations ensure is maintained?

The correct answer focuses on the necessity for organizations to maintain secure systems and applications as part of PCI DSS Requirement 6. This requirement emphasizes the importance of developing and maintaining secure systems and applications to protect cardholder data. Organizations are responsible for ensuring that all software, including web applications, mobile applications, and any systems that handle sensitive data, are secure throughout their lifecycle.

Maintaining secure systems and applications involves conducting regular security assessments, applying security patches, and implementing security best practices. This proactive approach helps to mitigate vulnerabilities that could be exploited and compromise cardholder data, aligning with the overarching goal of the PCI DSS to ensure a robust security posture.

On the other hand, the other options present more limited or less comprehensive scopes. Focusing solely on web applications, for instance, does not encompass other application types that also require vigilance. Similarly, while managing third-party vendor software is important, it does not capture the broader requirement to secure all systems and applications that interact with sensitive data. Therefore, the comprehensive view of maintaining secure systems and applications aligns best with the intent of PCI DSS Requirement 6.