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 drugs act through heptahelical (serpentine) receptors ? 
Select and explain. 
A. Insulin, B. Estrogen, C. Local anaesthetics, D. Salbutamol
D: Salbutamol
Answer: D: Salbutamol 
Explanation: None