Although a direct survey has yet to be produced, clearly the growing ubiquity of tablet computers in our country is leading to diminishing popularity of the original handheld entertainment—that is, books. In decades past, books were the primary source of print media, but one third of adults in our country now own tablet computers on which they can read electronic books, or e-books. And even as far back as eight years ago, before tablets had even hit the market, only about half of adults in our country said in a survey that they were reading a book at the present time.
Each of following would be useful to determine in order to evaluate the argument EXCEPT
【选项】
Whether more or less than half of adults in our country in decades past were reading a book at any given time
选项是否正确？