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 cause inhibition of CYP3A except : 
Select and explain. 
A. Saquinavir, B. Ritonavir, C. Itraconazole, D. Erythromycin
A: Saquinavir
Answer: A: Saquinavir 
Explanation: None