How can an administrator show the CPU usage of a virtual machine over the last month?

To show the CPU usage of a virtual machine over the last month, selecting the VM's Monitor tab and then choosing Overview is the most appropriate action. The Monitor tab provides access to performance metrics over a selected time frame, including historical data that encompasses CPU usage statistics.

The Overview section within the Monitor tab typically displays graphical representations and detailed metrics on various resource usages, such as CPU, memory, and storage, allowing administrators to assess trends and patterns over a defined period, including the last month. This visualization can help in analyzing performance, identifying potential bottlenecks, and planning resource allocation more effectively.

Other methods, such as viewing the VM's Summary tab, primarily provide real-time or brief historical data and do not offer the comprehensive historical analysis that the Monitor tab’s Overview section does. Therefore, it wouldn't be suitable for analyzing usage over an extended period like the last month.