Read the following four passages．Each passage is followed by several questions or unfinished statements．For each of them there are 4 choices marked A, B, C and D．Choose the one that fits best according to the information given in the passage．

　　I've always known that my son uses his cellphone a lot, but his cellphone bill last month really got my attention, He had received nearly 2, 000 text messages(短信), and had sent nearly as many．Of course, he was out of school for the summer, and communicating more with friends who were far away．However, I had to wonder how he found time to keep a summer job and complete a summer course in between all that typing with his thumb．

　　I was even more surprised to learn that my son is normal．Teenagers with cellphones send and receive an average of 2.272 text messages a month, Nielsen Mobile says, author of a book called The Dumbest Geheraiion：How the Digital Age Stupefies Young Americans and Jeopardizes(危害)Our Future

　　Some experts say that all that text messaging is making our children stupid, and unable to read nonverbal cues(非语言暗示)such as facial expressions, gestures, postures and other silent signals of mood and attitude．“Unlike telephoning, text messaging doesn^'t even allow tones or pauses to be sent to others,” says Mark Bauerlein

　　Beyond that, though, I^'m not sure I see as much harm as critics of the trend do．I^’ve written before on how I initially tried to control my sons texting．But over time, I^’ve seen that my son suffers no apparent bad effects, and that he gains a big benefit of easy and continuing contact with many friends．Also, the time he spends texting replaces the hours teenagers used to spend on the phone; he dislikes talking on the phone, and says he really doesn't need to do so to stay in touch．

　　I don't think texting makes children stupid．It may make them annoying, when they try to text and talk to you．And it may distract them from math problems or what they have to do for school．

　　I don^'t see that texting harms the ability of teenagers to communicate, either．My son is as good at interpreting nonverbal cues as any of the older members of our family．If anything, I’ve found him more engaged and easier to communicate with from a distance, since he's constantly available through texting, and responds with faithfulness and speed that any mother would find reassuring(安心的)．