Explanation
Cluster Synchronization is a mechanism that allows cluster members to share state information and maintain a consistent security policy. Cluster Synchronization uses two types of synchronization: Full Synchronization and Delta Synchronization. Full Synchronization transfers the entire Security Policy and state tables from one cluster member to another. Delta Synchronization transfers only the changes in the state tables. Cluster Synchronization uses two services for communication: TCP port 256 (CPHA) for Full Synchronization and UDP port 8116 for Delta Synchronization3. Therefore, the correct answer is A.
References: 3: Cluster Synchronization

Explanation
The Implicit Clean-up Rule is another name for the Clean-up Rule, which is the last rule in every policy layer.
The Clean-up Rule defines the default action for traffic that does not match any of the preceding rules in the layer. The default action is to drop the traffic and log it, but it can be changed by the administrator.
References: Training & Certification | Check Point Software, Check Point Resource Library

Explanation
According to the Check Point website, you can use the pre_upgrade_verifier tool to verify if your management server is ready to upgrade to R81.20. This tool checks the compatibility of your current configuration and database with the target version, and provides a detailed report of any issues or warnings. The other tools are either used for exporting or importing databases, or not valid tools. References: Upgrade Verification Service

Explanation
The deployment of Check Point API does not have the purpose of creating a customized GUI Client for manipulating the objects database. The Check Point API is a web service that allows external applications to interact with the Check Point management server using standard methods such as HTTP(S) requests and JSON objects. The Check Point API can be used to execute an automated script to perform common tasks, create products that use and enhance the Check Point solution, and integrate Check Point products with 3rd party solutions. However, creating a customized GUI Client for manipulating the objects database is not a supported or intended use case of the Check Point API.