Which occurred first, the granite intrusion labelled 7 or the fault labelled x-y?

The answer is - The fault labeled X-Y.

The fault is older than the granite intrusion. The intrusions, including this one too, are cutting through already formed layers  (there's the occasional exception), in this case that is through the fault. Under the pressure the granite massive has been moving gradually and came into a position to cut across the fault.
To put it into the simplest manner, you have to 'bake the cake first, then put candles on it'.

The correct answer is a)  a resource with a limited supply; it will run out.