Final answer:
The automation level of DRS described where DRS places VMs on suited hosts but requires manual approval for migrations is 'Partially Automated'.
Step-by-step explanation:
The automation level of DRS (Distributed Resource Scheduler) that is described by "When you power on a VM, DRS places it on the best-suited host. When the cluster becomes unbalanced, DRS displays recommendations for VM migration" is Partially Automated. In this mode, DRS will make recommendations for the placement of virtual machines and for balancing the load across hosts, but it will not automatically perform the actual migrations. Instead, an administrator needs to manually apply the recommendations. This is in contrast to the Fully Automated mode, where DRS would both make recommendations and automatically implement them without administrator intervention.