Answer:
The research question that best demonstrates Victoria's understanding of the subject of her research is: "During the tenure of Michelle Obama's "Let's Move!" campaign, how did childhood obesity rates change from year to year?"
Step-by-step explanation:
This research question is focused on the national impact of the "Let's Move!" campaign on childhood obesity in America, which is the main subject of Victoria's research. The question also specifically asks about changes in childhood obesity rates over time, which is a key aspect of understanding the campaign's impact. Additionally, the question is clear and specific, making it a good research question.
In contrast, the other research questions do not focus on the national impact of the "Let's Move!" campaign on childhood obesity in America. Instead, they focus on other aspects of the campaign, such as Michelle Obama's reasons for introducing it or the resources provided by the campaign. These are not the main focus of Victoria's research, and therefore do not demonstrate a good understanding of the subject.