This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
A drug has 80% absorption and hepatic extraction ratio is 0.4. Calculate the bioavailability of drug? 
Select and explain. 
A. 12%, B. 32%, C. 48%, D. 64%
C: 48%
Answer: C: 48% 
Explanation: Amount absorbed = 80% (80 molecules)Amount removed by the liver= 80*4/10= 32 molecules80-32= 48%Ref: Goodman and Gillman 12th ed/pg 20