請依下文回答第 16 題至第 20 題         College classrooms are often drab and dreary places. Walls are painted a variation of “institutional gray”；furniture is easy to clean, but uncomfortable and unattractive. Chairs are lined up in straight rows facing theteacher’s desk or lectern. In one study, over 80% of university students rated their classrooms negatively,describing them as ugly, cramped, stuffy, and uncomfortable. The research by environmental psychologists isbeginning to show that unattractive classrooms are not only unappealing； they may also adversely affectacademic performance.        A more carefully controlled study of classroom environments was conducted a few years ago. Theresearchers selected two identical classrooms located side by side in the psychology building. The controlclassroom, which they called the “sterile classroom,” had white walls, a gray carpet, and rows of plastic desks.Besides, an alcohol-based beautiful hand sanitizer was placed in the room for students to use. The experimentalclassroom, which they called the “friendly classroom,” was redecorated with the help of a design consultant.Several walls were painted bright colors, art posters hung on the walls, large plants added to the room, andcolorful Chinese kites hung from the ceiling. In addition to traditional desks, a part of the room was outfittedwith area rugs, color-coordinated cushions, and wooden cubes to provide nontraditional seating.      The researchers investigated how these two different environments affected performance in actual collegeclasses. Two professors teaching introductory psychology agreed to participate in the study although they werenot informed of the purpose of the research. When school began, each class was randomly assigned to one ofthe two rooms. Halfway through the term, the classes switched rooms. Thus, students in both classes spent halfthe term in the control room and half in the experimental room. Students were not told they were being studied；the switch in rooms was explained as occurring because the original room was needed for videotaping. Themost striking finding from this study was that students performed significantly better on regular course examswhen they were in the friendly rather than the sterile room.
【題組】16 According to this passage, the word “sterile” means__________  .
(A) lifeless
(B) clean
(C) empty
(D) safe