When extend selection is active, what is the keyboard short-cut for s…

The correct answer is Option (4) → Ctrl + Shift + end

With Extend Selection on, the shortcut that selects all data up to and including the last row uses Ctrl together with Shift. The book’s exercise question asks the same question, and its answer is (c) [Ctrl]+[Shift]; the paper writes this option as Ctrl + Shift + end.