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: Physiology
All the following  hormones have receptors on the plasma membrane of target tissues except: 
Select and explain. 
A. Thyrotropin, B. Glucagons, C. Estradiol, D. Epinephrine
C: Estradiol
Answer: C: Estradiol 
Explanation: None