问题详情

Why do doctors recommend folic acid supplements for pregnant women？
A．Because folic acid is effective in preventing the death of embryos.
B．Because the right amount of folic acid helps prevent neural tube defects.
C．Because a mouse study has shown folic acid causes birth defects in mice.
D．Because pregnant women eat fewer leafy vegetables than they need.请帮忙给出正确答案和分析，谢谢！