15. Health New words : calcium (n): an element (Ca) found in bones, teeth and milk products strengthen (v): to make stronger source (n): a place of origin; a place or thing form which another thing can be taken supplement (n): a thing added to increase or make stronger convert (v): to change According to the professor, what are 2 sources of Vitamin D? choose 2 answers(只有一个正确选项)) A. From strong bones. B. From calcium. C. Sunlight and Supplements from the store. D. From body