Which of the following best describes the function of the sentence in the hightlighted lines? A. It provides the reasoning behind a claim about the role of sleep in memory consolidation. B. It explains why a previous claim about sleep and memory is unsustainable. C. It demonstrates why wakefulness is central to the process of declarative memory consolidation. D. It emphasizes the limited role sleep plays in the process of declarative memory consolidation. E. It concedes that the consolidation of declarative memory does not depend entirely on one factor.