Zelda Is a Marathon Runner

Zelda is a marathon runner. She completes the marathon in 2 hours and 30 minutes. Which of the following is true regarding her fuel use during the marathon?

A) If she runs out of muscle glycogen at the 2-hour mark, she will not feel fatigue.
B) Anaerobic glucose breakdown, using muscle glycogen, will provide most of the ATP for the marathon.
C) Liver glycogen is the preferred fuel during intense muscular activity lasting less than 2 hours.
D) As exercise duration increases beyond 20 to 30 minutes, blood glucose will become increasingly important to spare muscle glycogen, so Zelda will have the ability to sprint across the finish line.