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
All of the following cross plasma membrane except: 
Select and explain. 
A. Epinephrine, B. Thyroxine, C. Androstenedione, D. Estrogen
A: Epinephrine
Answer: A: Epinephrine 
Explanation: None