Correct Response: D. Research has shown that fluent readers have higher levels of comprehension than readers who lack fluency. By the third grade, fluent readers have developed automatic word recognition, which allows them to focus on the meaning of what they are reading rather than expending significant cognitive resources on decoding words. Options A, B, and C are incorrect because achieving reading fluency does not necessarily mean that students know how to use metacognitive skills (A) or that they have already developed background knowledge at the level of a textbook (B). Having fluency also does not mean that a third-grade student is skilled enough to decode any level of text (C).