In regards to the discussion of pseduo coding this question and that fact that it might be a red hearing to give the information on no parent child relationship.

I belive that this is a great question, to those of us that have taken microsoft exams know, they are filed with questions worded such as these, they test you not only on your knowledge of the problem, but also on your ability to take the information given, discount what is not revelent to the issue and make your decision based on the facts given. Yes its a little hard to read and takes a minute to understand, but when faced with a issue in real life, no one is going to pseduo code the problem for you and take out what is not relevent.

The only answer of course is the correct answer given, complete rollback.

Also, Triggers are always run inside of a transaction by default, you do not have to explicity identifiy one.

my 2 cents