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
The basis of combining ritonavir with lopinavir : 
Select and explain. 
A. Pharmaceutical compatibility, B. CYP3A4 inhibition by ritonavir, C. Long elimination half life of ritonavir, D. Ability to counteract side–effects of lopinavir
B: CYP3A4 inhibition by ritonavir
Answer: B: CYP3A4 inhibition by ritonavir 
Explanation: None