19 The sentence “ _______ ” best expresses the central point of this passage. (A) College classrooms are often drab and dreary places. (B) In one study, over 80% of university students rated their classrooms negatively, describing them as ugly, cramped, stuffy, and uncomfortable. (C) The research by environmental psychologists is beginning to show that unattractive classrooms are not only unappealing; they may also adversely affect academic performance. (D) The researchers investigated how these two different environments affected performance in actual college classes.