47. The word "link" in line 23 is closest in meaning to (A) tension (B) connection (C) attraction (D) distance

45. According to the passage, scientists used isotopes from the water of the ice core to determine which of following? (A) The amount of air that had bubbled to the surface since the ice had formed (B) The temperature of the atmosphere when the ice was formed (C) The date at which water had become locked in the glacier (D) The rate at which water had been frozen in the glacier