Many congenital neurologic abnormalities can be prevented by the mother taking before conception and during early pregnancy.

Folic acid

Explanation:

The congenital neurologic abnormalities refer to the abnormalities which are present in the infant at the time of the birth like neural tube defects in the given question.

There could be many factors responsible for this like consumption of drugs and alcohol, exposure to mutagens or carcinogens, inadequate amount of folic acid and many others.

Folic acid is a type of Vitamin B which is involved in the production of new cells so are advised to the pregnant lady during and before conception. Consumption of folic acid reduces the chances of birth defects.

Thus, Folic acid is the correct answer.