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: Pharmacology
Which of the following receptors mediate the release of ACTH by Vasopressin? 
Select and explain. 
A. V1a, B. V2, C. V3, D. V4
C: V3
Answer: C: V3 
Explanation: Vasopressin acts on V3 or V1b receptors to release ACTH.