Researchers are conducting a study to determine the effects of vitamin d on the human body. the study involves providing pills t
hat contain vitamin d to one group of human subjects and pills that do not contain the vitamin or other active ingredients to another group of people. the pills that do not contain vitamin d are
I believe it’s the sun As the sun gives nutrients to the plant Plant gets satin by animal Animal gets eaten by animal and so on and the nutrients would be passed on
