A、None of them had been musically trained before. B、Only 6 of them had a knowledge of music before. C、Not all of them had been t

“Music lessons may improve memory and learning ability in young children by promoting different patterns of brain development,” a study shows.
    After a year of musical training, children aged between 4 and 6 performed better at a standard memory test than did children who were not taught music. The findings suggest that music could be useful for building the learning capacity of young minds.
    Earlier studies have shown that older children given music lessons become better at IQ tests than those who are musically untrained, but this is the first to show such a benefit in children so young.
    Professor Laurel Trainor, of McMaster University in Hamilton, Ontario, also found clear differences in the ways in which children’s brains responded to sound after a year of musical training. “This is the first study to show that brain responses in young musically trained and untrained children change differently over the course of a year,” she said. “These changes are likely to be related to the cognitive benefit that is seen with musical training.”
    Professor Trainor’s team looked at 12 children, 6 of whom had just started extra-curricular music lessons and 6 of whom were not being taught any music except that included as a standard part of their school curriculum. During the year all 12 children had their brains examined four times using MEG, and each child was played two types of sound — white noise and a violin tone. The MEG measurements showed that all children responded more to violin sounds than to white noise, reflecting a preference for meaningful tones, and their response times fell over the course of the year as their brains matured.  
Questions 32 to 35 are based on the passage you have just heard.
32. What is this passage mainly about?
33. What can be concluded from the passage?
34. What do we know about the twelve children tested in the study?
35. What do we know from the MEG measurements?