Vitamin d is unique in that it can be obtained by the diet but also is synthesized inside the body when a cholesterol-like substance is activated by sunlight and converted to the prohormone vitamin d. check all of the organs that participate in vitamin d synthesis and activation.

The organs that participate in vitamin D synthesis and activation are kidneys and liver.
Vitamin D is carried in the bloodstream to the liver, where it is converted into the prohormone calcifediol.Calcifediol is further hydroxylated by the kidneys to form calcitriol and calcitriol circulates as a hormone in the blood, and regulates the concentration of calcium and phosphate.

The answer should be geothermal i hope i’m right message me if i’m wrong and i’ll change my answer and fix it for you