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
In case of fasting, glycogen stores in the body can last up to: 
Select and explain. 
A. 7 days, B. 72-96 hours, C. 6-8 hours, D. 12-18 hours
D: 12-18 hours
Answer: D: 12-18 hours 
Explanation: Liver glycogen is the first-line of defence against hypoglycemia. The liver concentration of glycogen is about 450 mmol /L glucose equivalents after a meal, falling to about 200 mmol /L after an overnight fast. After 12 to 18 hours of fasting, liver glycogen is almost totally depleted.