A)4.8 kcal of energy liberated per liter of O₂ consumed B)4.8 kcal of energy liberated per liter of CO₂ expired C)5.8 kcal of energy liberated per liter of O₂ consumed D)5.8 kcal of energy liberated per liter of CO₂ expired E)6.8 kcal of energy liberated per liter of CO₂ expired