This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
I say only A, B are correct. D is incorrect according me, as wrapper can be used by any other class not only by filter implementing class, though we use mostly in filter implementing class. But no one restricts me from doing this.