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
Calcitriol acts on 
Select and explain. 
A. G protein coupled receptor, B. Cytosolic receptor, C. Intranuclear receptor, D. Enzymatic receptors
B: Cytosolic receptor
Answer: B: Cytosolic receptor 
Explanation: Bioactive vitamin D or calcitriol is a steroid hormone that has long been known for its impoant role in regulating body levels of calcium Nuclear or cytosolic receptors include the binding sites for steroid hormones, thyroid hormones, vitamin D, and retinoic acids Ref-Goodman and Gillman 12th/e p1282