According to the VMware vRealize Operations Install and Configure Guide1, when upgrading the vRealize Operations cluster via the Administration UI, the cluster status should change from offline to online after the upgrade process is completed. However, if the cluster status remains offline or fails during the upgrade, the administrator can use the Finish Installation option to resume the upgrade process. The Finish Installation option attempts to bring the cluster online and complete the upgrade. The administrator can monitor the progress of the upgrade from the Administration UI or the Cluster Management page.
The other options are not suitable for managing this problem and continuing the installation process. The Rollback Installation option is used to revert the cluster to the previous version of vRealize Operations, not to resume the upgrade process. The Rollback Installation option is only available if the cluster is online and the upgrade has failed. The administrator should not manually take the cluster offline, as this would interrupt the upgrade process and cause data loss or corruption. References:
1: VMware vRealize Operations Install and Configure Guide,
https://docs.vmware.com/en/vRealize-Operations/8.5/vrealize-operations-manager-85-installation-and-con page 54-55, 58-59

To discover custom application services running on virtual machines, the administrator needs to install the vRealize Operations Service Discovery Management Pack1. This management pack enables service and application discovery using the Service Discovery adapter, which leverages the Telegraf agent to collect data from the end point VMs2. The administrator can configure the Service Discovery adapter to discover predefined and custom applications and services, and view their relationships and metrics in vRealize Operations3. The administrator can also create custom application definitions based on object names, tags, or properties, and import them as XML files. Configuring a white list is not a valid option, as it is used to filter out unwanted services from discovery. References: 1: vRealize Operations Service Discovery Management Pack - VMware Docs(https://docs.vmware.com/en/vRealize-Operations/8.6/com.vmware.vcom.core.doc/GUID-B9095E9B-7F10 Service and Application Discovery - VMware Docs(https://docs.vmware.com/en/vRealize-Operations/8.10/com.vmware.vcom.core.doc/GUID-CC683117-D93 Configure Service and Application Discovery - VMware Docs(https://developer.vmware.com/apis/579/vra-advanced-designer/) : Create Application Definition - VMware Docs : Configure White List - VMware Docs

To change the subscription options for a datacenter migration scenario, the administrator can use the Change Plan option in the Scenario Builder. This option allows the administrator to modify the plan type, duration, and discount for the selected cloud provider without running a new scenario. The Change Plan option also updates the cost and savings estimates based on the new subscription options. The other options are not relevant for changing the subscription options. Change Cloud Provider is used to switch to a different cloud provider for the scenario. Edit Configuration is used to modify the configuration settings, such as CPU, memory, and storage, for the scenario. Edit Discount is used to apply a custom discount percentage for the scenario. References: Change Plan, Scenario Builder, Create a Scenario for Data Center Migration