Wonderful question, Tom (even though I got it wrong :(). It's good to know the difference between snapshot and serializable.
Am I the only one who noticed that the code was repeated? It was the same both times, but that made it harder, at first, to figure out what was going on: was it showing first code for transaction A, then code for transaction B, then code that was run later for transaction A, etc.?
I, for one, am glad it didn't specify the number of correct answers. If it had, then it would have been possible to figure out from that how many of the transactions completed successfully (0, 1, or 2).
Keep the complex questions coming!!!