During Intense (Heavy) Exercise, the Initial Ability of Oxidative Phosphorylation

During intense (heavy) exercise, the initial ability of oxidative phosphorylation to provide enough ATP for the sudden demand of increased force generation by the skeletal muscle is , thereby causing the muscle fiber to quickly and massively boost its energy production from _________until oxygen delivery and other mechanisms come up to speed.

A) enhanced : glucose
B) enhanced : fatty acids
C) inadequate : substrate -level phosphorylation
D) inadequate : fatty acids
E) enhanced : substrate -level phosphorylation