Instructions: You are given a science question (hard-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.
Input: The vampire finches in the Galapagos Islands peck at another species of bird, the blue-footed booby, until the finches make a wound. Then, the finches drink the booby's blood. Scientists think that many generations ago finches used to peck bugs off the booby, and the behavior evolved to what it is today. Which statement best describes the birds' relationship generations ago and the relationship today?
(A) The old relationship was parasitic. The new relationship is mutualistic. (B) The old relationship was mutualistic. The new relationship is parasitic. (C) Both relationships are parasitic. (D) Both relationships are mutualistic.
Output:
B