38. The word "unprecedented" in line 25 is closest in meaning to (A) not extensive (B) not used often (C) not existing before (D) not needing money

41. Why does the author mention ants and termites in line 6 ? (A) To give an example of food that chimpanzees collect by using tools (B) To emphasize that ants and termites often hide together in the same place (C) To identify an important part of the chimpanzee diet (D) To point out a difference between two closely related species