Which file from the virtual machine directory contains the suspended virtual machine's memory contents?

The file that contains the suspended virtual machine's memory contents is the .vmss file. When a virtual machine is suspended, its current state, including all memory contents, is saved to this file. This allows the virtual machine to be resumed later without losing any data or the state of operations at the time of suspension.

In contrast, the other file types serve different purposes in the context of a virtual machine. The .vmdk file is used for the virtual machine's disk data, storing the actual disk contents where the operating system, applications, and files reside. The .log file records operational logs of the virtual machine, which are useful for troubleshooting and maintaining the environment but do not contain memory data. The .vmx file holds the configuration settings of the virtual machine, such as hardware specifications and resource allocations, rather than the live memory state. Thus, the .vmss file is specifically designed to manage the state of a suspended virtual machine, making it the correct answer for this question.