Which of the following is an assessment that measures a student's reading fluency?

The assessment that measures a student's reading fluency is a timed oral reading passage followed by comprehension questions. This type of assessment focuses on how quickly and accurately a student can read aloud, demonstrating their fluency skills. Reading fluency encompasses not only the speed of reading but also the ability to read with appropriate expression and intonation, which can be observed during an oral reading task. Additionally, the comprehension questions that follow help gauge the student's understanding of the passage, providing insights into how well the student is processing the text.

In contrast, a written essay primarily assesses writing ability and creativity rather than reading skills. An untimed silent reading exercise doesn't measure fluency effectively since it removes the element of timed performance, which is crucial for evaluating how quickly a student can read. A spelling test focuses on vocabulary and orthographic knowledge instead of the fluency of reading text aloud. Therefore, the first assessment is most appropriate for evaluating reading fluency.