Correct Response: A. Option A is correct because, in the primary grades, the most common factor disrupting fluency is weak decoding skills. The key indicators of fluency are accuracy, rate, and prosody. In an oral reading fluency screening, a teacher uses a student's performance reading aloud a grade-level passage to take a quick measure of the students' overall reading development. Note that gaps in a student's phonics knowledge most directly affect reading accuracy, but inaccurate reading can also affect other fluency indicators (e.g., by causing a slow rate or choppy reading, by reducing a student's score in words correct per minute). Options B, C, and D are incorrect because the texts typically used in beginning-of-year, second-grade level screening assessments primarily feature words that represent the phonics skills and syllable types taught in first grade. Therefore, the complexity of the text would mostly likely not be at a level where vocabulary (B), language structure (C), or background knowledge (D) would be primary disruptors to oral reading fluency.