This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fuel in Fed, Fasting and Starvation, Subject name: Biochemistry
Increased formation of ketone bodies during fasting is a result of: 
Select and explain. 
A. Decreased level of circulating glucagon, B. Decreased formation of Acetyl CoA in the liver, C. Increased levels of free fatty acids in blood, D. Inhibition of b-oxidation of fatty acids in liver
C: Increased levels of free fatty acids in blood
Answer: C: Increased levels of free fatty acids in blood 
Explanation: Free fatty acids bound to albumin are increased as a result of an increased activity of Hormone sensitive lipase in adipose tissue as this enzyme breaks TG into glycerol & fatty acids. These fatty acids are taken up by liver. b-oxidation of these fatty acids in liver provides the acetyl CoA for ketogenesis. Hepatic ketogenesis is also stimulated by elevated levels of glucagon during fasting.