What is a valid way to configure an ElasticXL Cluster?

The correct answer is D. Check Point’s R82 ElasticXL deployment procedure requires the first appliance to run the Gaia First Time Configuration Wizard. In the Products window, the administrator selects Security Gateway, enables “Unit is a part of a cluster,” and selects ElasticXL. Completing the wizard creates an ElasticXL Cluster with its first member. Additional appliances are handled differently: Check Point explicitly states that the Gaia First Time Configuration Wizard is not run on additional Security Appliances that join the existing ElasticXL Cluster. Instead, they are detected and joined from the existing cluster by using the ElasticXL provisioning workflow, including the add cluster member command in Gaia gClish. Therefore, configuring every member through the wizard is wrong, while configuring only the first member through the wizard and adding subsequent members without FTCW is the documented R82 method.