Hello!
That's quite common here. Usually, at the distance they give you that clearance (got one yesterday from almost 200NM away!) your three options a, b and c lie within the same degree of heading so it dosen't really matter. If there is a significant distance between those points, I choose one that is most convenient for the type of approach to be expected and ask if it is OK to fly there. Until now, that has always been granted.
Another interesting direct-to-clearance here is something like "direct twentyone twelve" (got that one yesterday too....) which translates to direct 12 miles final runway 21. If in doubt, ask!
Regards - max