Which of the following is a common method for safeguarding cardholder data?

Implementing role-based access controls is a robust method for safeguarding cardholder data because it restricts access to sensitive information based on the user's job responsibilities and needs. This ensures that only authorized personnel can access or manage cardholder data, reducing the risk of unauthorized access and helping to maintain confidentiality and integrity.

In a PCI DSS compliant environment, proper access control mechanisms are essential not only for protecting cardholder data but also for demonstrating accountability within the organization. By assigning specific roles and privileges, organizations can minimize the potential attack surface and protect against insider threats.

The other methods listed in the choices are not effective for data protection. Storing cardholder data in plain text exposes it to theft and misuse, while utilizing guest accounts can lead to uncontrolled access, undermining security protocols. Disabling encryption protocols makes data vulnerable to interception and exploitation, which goes against best practices for safeguarding sensitive information.