Under Which of the Following Conditions Could an Athlete Expect

Under which of the following conditions could an athlete expect performance to begin to suffer if no additional glucose is ingested?

A) After 1 hour of moderate-intensity exercise (60% to 85% VO₂ max) , when blood glucose levels dwindle.
B) After 1 to 3 hours of continuous moderate-intensity exercise (60% to 85% VO₂ max) , when glycogen becomes depleted.
C) After 5 to 6 hours of continuous low-intensity exercise (50% to 60% VO₂ max) , when blood glucose levels dwindle.
D) After 30 minutes of continuous high-intensity exercise (70% to 90% VO₂ max) , when glycogen becomes depleted.