I choose option A. Imagine your standard action is quarter. You want to use your quarter to buy some gum from a machine - but when you try to use your quarter, a bully knocks you down and you lose your quarter. The gum is still there, waiting - until you get another quarter. In effect, you "spend" your standard action to activate a power. Should something prevent you from "spending" that action, you haven't activated your power yet - although your action is still lost until you get more.
Not to twist your analogy beyond all relevance - but the quarter is still there
also. Unless the bully picks the quarter up and walks away with it - and there isn't an analagous ability to pick up your powers and walk away with them (at least not yet).
But of course - trying to compare a power or ability to a physical object like a quarter is odd, to say the least.
If I wanted to argue in favor of "losing the power", I would point to the disruption of spell in earlier versions. You start casting the spell, someone interrupts your spell, the spell is lost.
But as it happens, while I agree that you
do lose the power (excepting reliable powers), I
disagree that it is because the power and the action are the same thing. The rules for the interrupt specify that you lose the power and this
does not (imho) automatically mean that you lose the power. But it also does not mean that you retain the power - rather you lose the power
because you already started to use it.
Note:
An opportunity action takes place before the target finishes its action. This does
not say 'before the target
initiates its action. It is the initiation of the action which both triggers the OA
and which expends the power.
As I see it, you initiate your power. At this point, the power has been expended, and even if something causes the power to later have no effect (i.e. player goes unconscious, target becomes invalid, player decides not to complete the action, etc.) the power is no longer available (exception: reliable powers). So if you are dropped before you can complete the action, the power is not lost because the attack caused you to lose the power, the power is lost
because you already initiated it. The power fails to complete because the attack caused you to lose the opportunity (the action) and therefore you were unable to complete it. I.e. - the loss of the power is due to the players starting to use the power and, indirectly, because conditions made it impossible for the power to be used.
That said, I can see why someone might want to house rule a concentration check type rule to allow a character to retain their power, or (better yet, imho) allow them to immediately expend a healing surge to choose to retain the power. But these would be house rules and not RAW/I.
Carl