The correct answer is:
C. "Before the paper rights could become actual rights, someone had to interpret what the language of the Bill of Rights meant in specific situations." (Paragraph 14)
This detail provides the best clue for the meaning of "arbiter," as it emphasizes the need for someone to interpret and make decisions regarding the application of the Bill of Rights in various contexts. An "arbiter" is someone who has the authority to decide or settle a dispute.