Final answer:
It is true that when adding or moving a host to a vSphere DRS cluster, you can either create a resource pool for the host's VMs and resource pools to maintain the existing hierarchy, or you can discard it.
Step-by-step explanation:
When adding a host or moving a host into a vSphere DRS cluster, it is true that you can create a resource pool for the host's VMs and resource pools, which will keep the resource pool of the existing host. Alternatively, you have the option to discard the existing resource pool hierarchy. This flexibility allows administrators to manage resources in a way that is best suited to their specific environment and ensures that the performance and availability of virtual machines are maintained according to the needs of the business.