Why Is Folate Supplementation Recommended for Women One Month Before

Why is folate supplementation recommended for women one month before conception and during the first trimester of pregnancy? 

A)  To reduce the risk of gestational diabetes 
B)  To prevent severe morning sickness 
C)  To prevent neural tube defects, such as spina bifida, which may occur during the early weeks of pregnancy. 
D)  To help reduce the risk of iron-deficient anemia. 
E)  To help ensure a healthy maternal weight gain during pregnancy.