What does a vApp do in VMware vSphere?

A vApp in VMware vSphere is essentially a container that facilitates the grouping of multiple virtual machines for more efficient management and deployment. Its primary purpose is to create a logical structure where related virtual machines can be managed as a single entity, simplifying tasks such as resource allocation, resource management, and configuration.

By using a vApp, you can efficiently control the operational aspects of the grouped VMs, such as setting dependencies, resource settings, and guest customization. This allows for easier orchestration of applications that have components spread across various VMs, enhancing deployment speed and ensuring that the specified startup and shutdown orders are maintained.

In contrast, the other choices do not accurately describe the function of a vApp. A vApp does not act as a single instance of a virtual machine, provide backup solutions, or serve as an external network connection. Instead, it specifically focuses on the management and orchestration of multiple VMs that work together, thus emphasizing the correct choice.