The entire argument about question 1 is redundant as you'll find out the answer in December anyway. Although, I put D - mutual understanding because it seemed the most correct. Social Justice is an initiative not a purpose, and unification could be construed as correct, however I think that the word unify means to become a single unit and I doubt any Christian variants have that as an ideal of their church. I think people are getting unity and unify mixed up. You can have unity without unification, just as you can have unification without unity. They're separate ideas.
No, you are quite mistaken. Unity is the state of being united or joined as a whole, whereas, unification is the process of being united or made into a whole. You can't have unity without unification; it's that essential link, which needs to be understood. They are mutual ideas, and need each other in order to have some relevant meaning. Now by these strict definitions, the dialogue is the medium in achieving such unity, therefore, the purpose of dialogue must be of unification if we are to result in unity. I can accept the argument for mutual understanding, but the argument for unification has its merits as well.
And the argument isn't redundant. If there wasn't any argument in 2009, then that MC couldn't have resulted in two correct answers. Discussion is required to determine the correct answers, and using relevant evidence, can indeed result in a solution which benefits both sides of this argument.