You want to manually failover the primary Routing Engine in an SRX Series high availability...

To manually failover the primary Routing Engine in an SRX Series high availability cluster pair, you need to issue the request chassis cluster failover redundancy-group group-id node node-id command on the primary node, where group-id is the redundancy group number and node-id is the node number of the secondary node. This command initiates a graceful failover of the specified redundancy group to the secondary node, making it the new primary node. The other options are not necessary or correct for this task. Option A would disable the chassis cluster and reboot the primary node, which is not a graceful failover. Option B is not relevant, as the control link recovery solution is used to restore the control link connectivity between the nodes, not to initiate a failover. Option D would not trigger a failover, as the priority of the secondary node would only take effect after a reboot or a control link failure. References:

Chassis Cluster Redundancy Group Manual Failover

Initiating a Chassis Cluster Manual Redundancy Group Failover

SRX Getting Started - Troubleshoot High Availability (HA)