challenge: What was the general tone of the critical reception of the book 'Eternity: Our Next Billion Years'?
  
  A. Generally negative, with most reviewers criticizing the book's lack of scientific rigor
  B. Mixed, with most reviewers feeling that the book was too focused on science fiction themes
  C. Overwhelmingly positive, with all reviewers praising the book's depth and insight
  D. Mixed, with some reviewers praising the book's accessibility and others criticizing its superficiality
  Answer: 