It's a good book, but they got a little sloppy, especially towards the end.
You should check out the
errata Somewhat inconveniently, there is the confirmed errata on the latest printing (some of which seem to be fixed anyway in my book), a set of unconfirmed errata (many of which are wrong, while many others are right), and changes fixed from old printings.
It seems to me you have an old printing because question 4 in my book only shows answer A as correct. For question 12, I think B and D are both correct, but I could be wrong.