Which command is used to create custom snap-ins in the Windows environment?

The command used to create custom snap-ins in the Windows environment is mmc.exe. The Microsoft Management Console (MMC) allows users to create, save, and open management tools called consoles. Snap-ins are the individual tools that provide specific management capabilities, such as managing hardware, software, or network resources. By using mmc.exe, users can add or configure snap-ins according to their needs, which is essential for effective system administration and management in Windows.

The other options provided do not serve this purpose. cmd.exe is the command-line interpreter for executing commands and scripts, PowerShell (powershell.exe) is a task automation and configuration management framework primarily concerned with complex scripting and management tasks, and taskmgr.exe is the Task Manager, used for monitoring system processes and performance rather than creating management consoles.