Final answer:
The best example of the diagnostic component of formative assessment is when students complete the K and W parts of a KWL chart about the Great Depression.
Step-by-step explanation:
The best example of the diagnostic component of formative assessment is option C: Students complete the K and W parts of a KWL chart about the Great Depression. The diagnostic component of formative assessment involves gathering information about students' prior knowledge and understanding of a topic. Completing the K (What I know) and W (What I want to know) parts of a KWL chart helps students reflect on their existing knowledge and identify gaps in their understanding, which is essential in diagnosing their learning needs.