Here is my best evaluation from what I'm understanding of the passage....
(A.) Protection
Although it does not directly say the branches stand for protection, we can infer this to be true. The words "beneath the shade of the spreading branches of the Tree of Peace," show the safety that connection has brought the tribe. It is the coming together that has allowed for the growth of these "branches" and the further developement of peace. Given the relevance of connection in the passage, it's easy to think (B.) would be the answer. To see why the answer is (A.), the reader must recognize the fact that this tree may have come from connection, but it's branches represent the peace and protection that resulted from it.
