Most people think that the older you get, the harder it is to learn a new language. That is, they believe that children learn more easily and efficiently than adults. Thus, at some point in our lives, maybe around age 12 or 13, we lose the ability to learn languages well. Is this idea a fact or myth ? Is it true that children learn a foreign language more efficiently than adults? On the contrary, research studies suggest that the opposite may be true. One report, on 2,000 Danish children studying Swedish, concluded that the teenagers learned more, in less time, than the younger children. Another report, on Americans learning Russian, showed a direct improvement of ability over the age range tested; that is, the ability to learn increased as the age increased, from childhood to adulthood. There are several possible explanations for these findings. For one thing, adults know more about the world and therefore are able to understand meanings more easily than children. Moreover, adults can use logical  thinking to help themselves see patterns in the language. Finally, adults have more self-discipline (self-control) than children. All in all, it seems that the common idea that children are better language learners than adults may not be a fact, but a myth. Which of the following possible explanations for older student's better achievement is not mentioned in the above passage?
Adults know more about the world. Adults can use logical thinking Adults have more self-discipline. Adults can read better.