Which of the Following Is a Characteristic of Vitamin D

Which of the following is a characteristic of vitamin D nutrition?

A) Vitamin D deficiency may be created by a calcium deficiency
B) Only about one-half of the world's population relies on sunlight to maintain adequate vitamin D nutrition
C) Prolonged exposure to sunlight degrades the vitamin D precursor in skin,thus preventing vitamin D toxicity
D) In people living in northern U.S.cities,vitamin D stores from synthesis during the summer are usually sufficient to meet the needs during the winter