Very nice question @bitbucket-25253.
I got it wrong because I couldn't choose between 50% and 90%. I knew the heap writes all over the place and that shrink "usually" drives fragmentation over 90%. However in this case I was struggling with the fact that there's only 2 tables. Given that only 1 table was left I was think that all the page would move to the front an be "somewhat" in order.
Loved this question, just giving you pointers for the next ones :-).