Anon:
They "can" change at any time, but that's not really in the PM's wheelhouse. Let me try to explain:
With respect to regulation and industry standards, change is announced and implementation dates are given. If you're expecting a change in a regulation or standard that may impact your project, you plan for that risk. They just don't magically change overnight; it's not how regulations work. (Speaking from a strict US perspective here). They are things that are outside PM control, but thankfully do not normally change rapidly or without warning.
Second and probably more importantly, the exam is on what the PMBOK says, not what you think it should say. All questions must be answered from the perspective of the PMBOK guide, not how you personally would do business.
Good luck!
Harry