This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pharmacology, Subject name: Pharmacology
Which of the following is calculated as the ratio of the area under the curve (AUC) obtained by oral administration vs. the AUC for intravenous administration of the same drug? 
Select and explain. 
A. Absorption, B. Bioavailability, C. Clearance, D. Elimina on rate constant
B: Bioavailability
Answer: B: Bioavailability 
Explanation: bioavailabilitygenerally refers to the fraction of drug absorbed systemically, and is thus available to produce a biological effect. This is often measured by quantifying the "AUC". In order to determine the respective AUCs, the serum concentration vs. time plots are typically gathered using C-14 labeled drugs and AMS (accelerated mass spectroscopy). Ref k d tripati 6/e p27