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Question 1·Hard·Transitions

During prolonged fasting, the liver converts fats into ketone bodies, which can provide much of the brain's energy. Describing this change as the brain "switching from glucose to ketones" therefore captures a genuine shift in the brain's main fuel. The wording can also be misleading, however: some brain cells and metabolic processes continue to require glucose, and the liver keeps releasing a limited supply of it. ______ the description remains useful as shorthand, provided it is not taken to mean that glucose use stops entirely.

Which choice completes the text with the most logical transition?