Some parents will buy any high-tech toy if they think it will help their child, but researchers said puzzles help children with math-related skills.Psychologist Susan Levine, an expert on mathematics development in young children the University of Chicago, found children who play with puzzles between ages 2 and 4 later develop better spatial skills. Puzzle play was found to be a significant predictor of cognition(认知) after controlling for differences in parents'income, education and the amount of parent talk, Levine said.The researchers analyzed video recordings of 53 child-parent pairs during everyday activities at home and found children who play with puzzles between 26 and 46 months of age have better spatial skills when assessed at 54 months of age.“The children who played with puzzles performed better than those who did not, on tasks that assessed their ability to rotate(旋转)and translate shapes,” Levine said in a statement.The parents were asked to interact with their children as they normally would, and about half of children in the study played with puzzles at one time. Higher-income parents tended to have children play with puzzles more frequently, and both boys and girls who played with puzzles had better spatial skills. However boys tended to play with more complex puzzles than girls, and the parents of boys provided more spatial language and were more active during puzzle play than parents of girls.The findings were published in the journal Developmental Science.4. What is the text mainly about?
选项：

A:A mathematical method. ;
B:A scientific study.;
C:A woman psychologist ;
D:A teaching program