Which is the best example of a well-defined research question?

The choice indicating how early preschool programs like Head Start affect student preparedness for statewide 2nd grade exams is a strong example of a well-defined research question because it is specific, focused, and measurable. This question not only identifies a particular program (Head Start) but also ties it to a specific outcome (student preparedness for 2nd grade exams). This creates a clear framework for research, allowing for the collection of data that can be analyzed to derive findings about the impact of preschool programs on academic performance.

In contrast, the other options are more vague or subjective and do not lend themselves to systematic investigation. For instance, asking what one should eat for lunch today is personal and immediate, lacking the broader implications or context necessary for research. The question about yoga, while it discusses a topic of interest, is too broad without specifying which benefits or how they might be measured. Similarly, asking how to get better at a job is not specific enough to generate researchable data, as it does not focus on a particular aspect or outcome related to job performance.

Thus, the clarity and specificity of the selected question make it the best example of a well-defined research question.