Tokenization is the best solution to protect payment card data from unauthorized disclosure when moving to the cloud. Tokenization replaces sensitive card data with unique identifiers (tokens) that have no exploitable value outside the tokenization system. Even if the data is compromised, the attacker would not obtain actual card numbers. This is in line with PCI DSS requirements for protecting payment card information.

The tools that can be used to provide key information in the risk register are SCAP scanner and vulnerability scanner. SCAP stands for Security Content Automation Protocol, which is a set of standards and specifications for automating the management of security configuration, vulnerability assessment, and compliance evaluation. SCAP scanner is a tool that can scan systems and networks for security issues based on SCAP content. Vulnerability scanner is a tool that can scan systems and networks for known vulnerabilities and weaknesses. These tools can help the security analyst identify and prioritize the risks associated with the systems and networks, as well as provide possible remediation actions.

Explanation
A screened subnet is a network segment that separates two different environments, such as (operational technology) and IT (information technology), and provides security controls to limit and monitor the traffic between them. This would allow the business to get the required reports from the historian server without exposing the environment to unnecessary risks. Using a VPN, allowing IT traffic, or allowing PLCs to send data are less secure options that could compromise the environment. Verified References:
https://www.comptia.org/blog/what-is-operational-technology
https://partners.comptia.org/docs/default-source/resources/casp-content-guide

Segmentation isolates the vulnerable server into a separate network segment, reducing its exposure to potential attackers. By implementing firewalls or virtual LANs (VLANs), segmentation minimizes the risk of lateral movement and external exploitation, aligning with CASP+ objective
1.3, which emphasizes implementing appropriate compensating controls to address vulnerabilities.

Key escrow is a process that involves storing encryption keys with a trusted third party, such as a CASB (Cloud Access Security Broker) or a government agency. Key escrow can enable authorized access to encrypted data in case of emergencies, legal issues, or data recovery. However, key escrow also introduces some risks and challenges, such as trust, security, and privacy.References:
https://www.techopedia.com/definition/1772/key-escrowhttps://searchsecurity.techtarget.com/definition/key-escr