An administrator has an existing vRealize Operations instance that monitors an existing vSphere infrastructure.

According to the vRealize Operations User Guide1, the action that the administrator should take to accomplish the goal of configuring vRealize Operations to monitor the new NSX-T installation is to add an NSX-T account under Cloud Accounts. An NSX-T account is a configuration that defines the connection details and credentials of the NSX-T Manager instance that manages the NSX-T components across the vSphere infrastructure. By adding an NSX-T account under Cloud Accounts, the administrator can enable vRealize Operations to collect data from the NSX-T Manager instance and monitor the health, performance, capacity, and configuration of the NSX-T components, such as transport nodes, transport zones, logical switches, logical routers, and firewall rules. The guide provides the steps to add an NSX-T account under Cloud Accounts using the vRealize Operations user interface1. The other options are not correct because:

Configuring NSX-T account in Integrations is not a valid action, as there is no such option in the vRealize Operations user interface. The Integrations option under Administration is used to configure the integration of vRealize Operations with other VMware products, such as vRealize Log Insight, vRealize Automation, and vRealize Business for Cloud1.

Configuring NSX-T monitoring under the Cloud Account of the existing vCenter Server of the vSphere infrastructure is not a valid action, as there is no such option in the vRealize Operations user interface. The Cloud Account of the existing vCenter Server is used to monitor the vSphere components, such as clusters, hosts, datastores, and virtual machines, but not the NSX-T components1.

Adding NSX-T account under Other Accounts is not a valid action, as there is no such option in the vRealize Operations user interface. The Other Accounts option under Administration is used to add accounts for other types of cloud services, such as AWS, Azure, Google Cloud, or Kubernetes1. References: 1: vRealize Operations User Guide, pages 17-18, 21-22, 25-26.