A) This option is incorrect. Family history of congenital heart diseases is a significant risk factor. If a close family member has had a congenital heart defect, the risk of recurrence in subsequent pregnancies may be higher.

B) Correct answer. Exposure to certain infections during pregnancy, such as rubella (German measles), can increase the risk of congenital heart diseases in the baby. Rubella is known to be teratogenic, meaning it can cause birth defects.

C) This option is incorrect. While a healthy lifestyle during pregnancy is important for overall maternal and fetal health, it is not the primary risk factor for congenital heart diseases.

D) This option is incorrect. While genetic factors play a significant role in the etiology of congenital heart diseases, there are other identifiable risk factors, as mentioned in option B.