Passage 2      With more than 10 billion nerve cells, the human brain is by all odds the most complicated thingin the universe. Scientists still know relatively little about how the brain works. Averagely, the adulthuman brain weighs about three pounds and bulks the size of a grapefruit. In men the averageweight is about 1370g; in women about 1200g.
     The brain is the physical organ most associated with mind, a non-technical term used to refer tothe functions of the brain like problem-solving and remembering. It is part of the invisible world ofthought, including cognitive aspects such as perception and imagination, as well as noncognitiveaspects such as emotion. No one knows yet how mind and brain are related. In other words, no oneknows much about what happens in the brain when it is functioning.
      It is suggested that man ought to do better than he does with his much greater number of nervecells in that the ant achieves its marvelous community organization with only 250 nerve cells.However, the ants run their society by instinct not by thought. In fact, it seems likely that antscannot think at all; they use their nerve cells for receiving impressions of the outside world, not forcoping with it.
      Deep inside man’s brain is a core called “old brain,” which dinosaurs possessed millions ofyears ago. This core plays a part in arousing and satisfying primitive needs like hunger and sexuality.The old brain is covered by the dome of the neocortex, or “new brain,” which enables man to lookahead. It is the brain’s analytical computer, processing data and responsible for sensory perception,attention, memory, etc. Of all the forms of life, only man has the ability to plan for his future.
41. How big is the adult human brain?
(A) It is approximately the size of a mushroom.
(B) It is approximately the size of a grapefruit.
(C) It is approximately the size of a grape.
(D) It is approximately the size of an egg.