The MAXIMUM number of commands whose effect can be undone by the UNDO command is?

The correct answer is choice (d) all commands issued since the drawing was last loaded into the drawing editor.

(d) >>>>>>>>>>>>>>>>>>>>>>>all commands issued since the drawing was last loaded intothe drawing editor 

we can undo the All commands till open the drawing so it means the  Option- D is the correct answer "all commands issued since the drawing was last loaded in to the drawing editor "

You can undo all the commands issued from the moment you opened the drawing, but if you do that, don't save and open again.......

I agree with the statements  above which have chosen option (d)