The correct answer is B) R80.10 and later.
According to the Check Point documentation1, the Multi-Version Cluster Upgrade (MVC) is a new feature in R80.40 and higher that replaces the Connectivity Upgrade (CU) method. MVC allows you to upgrade a cluster to a newer version without a loss in connectivity and test the new version on some of the cluster members before you decide to upgrade the rest of the cluster members. The MVC feature supports the following destination versions2:
R80.10
R80.20
R80.30
R80.40
R81
R81.20
The other options are incorrect because they are either not supported by MVC or they are older than the source version (R80.40).
Reference:
Multi-Version Cluster (MVC) replaces Connectivity Upgrade (CU) in R80.401 ClusterXL upgrade methods and paths2

SecureXL uses templates to accelerate the connection rate by creating a connection entry in the SecureXL Connections Table without notifying the Firewall kernel for a predefined period of time1. This reduces the load on the Firewall kernel and improves the performance of new connections1. SecureXL uses five attributes to identify a connection and create a template: source address, destination address, source port, destination port, and protocol2. These attributes form a unique 5-tuple that defines a connection2.

You will find the config.txt file in the home directory of your user account (e.g. /home/admin/)1. The save configuration config.txt command is a Clish command that saves the current Gaia configuration to a text file2. The file is stored in the home directory of the user who executed the command, and it can be accessed by using the cat or less commands in expert mode1. The file can also be transferred to another machine by using the scp or sftp commands1. The config.txt file contains the Clish commands that are needed to restore the Gaia configuration to the same state as when the file was saved2. The file can be used for backup, migration, or troubleshooting purposes2.

To ensure that VMAC mode is enabled, the CLI command that should be run on all cluster members is fw ctl get int fwha_vmac_global_param_enabled; result of command should return value 1. VMAC mode is a feature that allows ClusterXL to use virtual MAC addresses for cluster interfaces, instead of physical MAC addresses. This improves the failover performance and compatibility of ClusterXL with switches and routers. To check if VMAC mode is enabled, the command fw ctl get int fwha_vmac_global_param_enabled can be used, which returns 1 if VMAC mode is enabled, and 0 if VMAC mode is disabled.

Check Point ClusterXL Active/Active deployment is used when there is Load Sharing solution set up. Load Sharing is a ClusterXL mode that allows distributing the network traffic between all cluster members, while still providing high availability in case of failures. Load Sharing can be configured as either Unicast or Multicast, depending on the network topology and switches support. Reference: R81 ClusterXL Administration Guide, page 9.