Users are reporting slow performance on a virtual server. An administrator notices that the virtual CPU is at 50%. Which of the following should the administrator check on the host?

I/O throttling limits disk or network input/output and would primarily affect storage or network performance, not directly virtual CPU performance at 50%.

CPU wait time indicates that the virtual machine's vCPUs are ready to process tasks but are waiting for physical CPU resources from the host, suggesting the host's physical CPUs are oversubscribed or experiencing contention.

Swap files are related to memory management, where a system uses disk space as an extension of RAM; while excessive swapping can cause slowdowns, CPU wait time is a more direct indicator of CPU resource contention.

Memory ballooning is a hypervisor technique to reclaim memory from guest VMs when the host is under memory pressure, affecting memory performance rather than directly explaining a 50% virtual CPU bottleneck.