Vitamin D is unique because in the presence of sunlight, skin cells can synthesize a sufficient supply of vitamin D, which is why it is also correctly classified as a conditional vitamin or as a ______.Multiple choice question.calcitriolprohormonetocopherolretinoid

Vitamin D is different from other vitamins in that it has a site of synthesis that is different from the location of action, so it is considered to be a _______.Multiple choice question.enzymelipaseprohormonenonessential nutrient

Which type of light is responsible for the synthesis of vitamin D in the skin?Question 22Select one:a.Infrared radiationb.Ultraviolet radiationc.Visible lightd.X-rays

Vitamins isolated from foods are classified as ____.Multiple choice question.provitaminsnaturalprevitaminssynthetic

Vitamins A, D, E, and K are considered to be _____ vitamins.Multiple choice question.water-solublefat-soluble

Which of the following is the term used for the biologically active forms of vitamin A?Multiple choice question.RetinoidsTocopherolsPhylloquinoneAscorbic acid