If an application is frozen and cannot be closed, what tool should be used?

When an application is frozen and cannot be closed through normal means, the appropriate tool to use is taskkill. This command allows users to forcibly terminate a process that is no longer responding. By using taskkill, you can specify the name of the application or its process ID (PID), which can effectively free up system resources and restore normal functionality to the system.

In contrast to this, tasklist is more of an informational tool. It provides a list of currently running processes, which can help you identify which application is unresponsive, but does not offer a way to terminate them. Meanwhile, the shutdown command is intended for shutting down or restarting the entire system rather than managing individual applications or processes. Lastly, convert is utilized for filesystem conversions and has no relevance to application management or process termination. Therefore, taskkill is the most effective and direct solution when you need to handle a frozen application.