Windows Disk-Image File: What to Exclude from Time Machine?

I don't use Parallels very often, but when I do, the famous, predictable annoyance comes up: The Windows disk-image file under MacOS gets tweaked, and then suddenly Time Machine has this mondo-huge 25GB file to backup. That of course, clogs up my Time Machine backup drive.

A common solution appears to be to exclude that file from Time Machine, and then back it up by some other means. OK, I'm cool with that, if only I knew what that file is called, and where I could find it, so that I can tell Time Machine to exclude it.

I'm guessing it's somewhere down in System or System Folder?