This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
U shaped dose response curve is seen in 
Select and explain. 
A. Vitamins, B. Anti cancer drugs, C. Steroids, D. Chelators
A: Vitamins
Answer: A: Vitamins 
Explanation: U shaped response curve is seen in vitamins Ref-Goodman and Gillman 12/e p74