What is "vSphere Update Manager" used for?

vSphere Update Manager is specifically designed for patching and upgrading ESXi hosts as well as managing the patching of virtual machines (VMs). This tool simplifies the maintenance of the vSphere environment by automating the patching process, which helps ensure that the infrastructure is up to date with the latest security and performance updates. It can automate the process of downloading patches, creating baselines, and applying the patches to hosts and VMs, thereby minimizing downtime and streamlining operations in a virtualized environment.

While other options involve important vSphere functionalities, they do not encompass the specific capabilities that vSphere Update Manager is known for. Migrating VMs, monitoring network traffic, and managing VM snapshots are all critical tasks in virtualization management, but they fall under different tools and features within the VMware ecosystem, such as vMotion for migration, vRealize Operations for monitoring, and built-in snapshot management within the VM's settings. Therefore, the focus of vSphere Update Manager remains on patching and updates, making option B the correct choice.