Which component is crucial for simplifying administration of virtual machines?

The management server plays a critical role in the administration of virtual machines by providing a centralized platform for managing and controlling the virtual environment. It simplifies the processes involved in deploying, monitoring, and maintaining virtual machines, allowing IT administrators to manage multiple systems from a single interface. This centralization reduces complexity and enhances operational efficiency, making it easier to allocate resources, apply configurations, and enforce policies across the virtual environment.

In contrast, the other components indicated — such as the network router, client application, and database server — do not focus primarily on virtual machine administration. The network router is responsible for directing traffic and connecting networks, while the client application typically serves as an interface for end-users to interact with the virtual machines rather than manage them. The database server stores data and supports applications but does not inherently provide the functions required for efficient administration of virtual machine infrastructure. Therefore, the management server's role is vital for streamlining and simplifying the complexities of managing a virtualized environment.