This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Vitamin also acting as hormonea) Vitamin Db) Vitamin Ac) Vitamin B1d) Vitamin C 
Select and explain. 
A. ac, B. a, C. ab, D. bc
C: ab
Answer: C: ab 
Explanation: Vitamin A and vitamin D are actually hormones which act on intracellular receptors (steroid receptor family).