If English means endless new words,difficult gramrnar and sometimes strange pronunciation,you are wrong．Haven’t you noti

 If English means endless new words,difficult gramrnar and sometimes strange pronunciation,you are wrong．Haven’t you noticed that you have become smarter since you started to learn a language?
    According to a new study by a British university,learning a second language can lead to an increase in your brain power,Researchers found that learning other languages changes grey matter．This is the area of the brain which processes information．It is similar to the way that exercise builds muscles．
    The study also found the effect is greater,the younger people learn a second language.
    A team led by Dr Andrea Mechelli,from University College London,took a group of Britons who only spoke English．They were compared with a goup of “early bilinguals．’’who had learnt a second language before the age of five,as well as a number of later learners．
    Scans showed that grey matter density(密度)in the brain was greater in bilinguals than in people without a second language．But the longer a person waited before mastering a new language,the smaller the difference.
    “Our findings suggest that the structure of the brain is changed by the experience of learning a second language,”said the scientists.
  It means that the change itself increases the ability to learn．
     Professor Dylan Vaughan Jones of the UniversityofWaleshas researched the link between bilingualism and maths skills.‘‘Having two languages gives you two windows on the world and makes the brain more flexible,”he said．“You are actually going beyond language and have a better understanding of different ideas．”
    The findings were matched in a study of native Italian speakers who had learned English as a second language between the ages of 2 and 34.Reading,writing,and comprehension were all tested．The results showed,that the younger they started to learn,the better．“Studying a language means you get an entrance to another world,’’explained the scientists．
 44．We may know from the scientific findings that        
A．the experience of learning a second language has bad effect on people’s brain
B．there is no difference between a later second language learner and one who doesn’t know a second language
C．the earlier you start to learn a second language,the higher the grey matter density is
  D．the ability of learning a second language is changing all the time
我的问题是A选项为什么不对?