Which vitamin is synthesised in the human body in the presence of sunlight?

Why does the requirement for iron increase significantly during pregnancy?

Which of the following statements are correct regarding the specific physiological roles of dietary minerals in regulating blood pressure? A. Sodium causes water retention, which leads to an increase in blood pressure. B. Potassium helps counteract the effects of sodium and relaxes blood vessels. C. Calcium's specific physiological role is aiding in vasodilation. D. Magnesium helps in vasodilation, which is the relaxation of blood vessels. Choose the most appropriate answer from the options given below: