Answer:
The source which would most likely yield the best information for the article is the following one:
A direct interview with five teenaged girls who love to shop for clothing and shoes.
Explanation:
It is a direct source, and as so it can offer the most reliable information. Plus, teens tend to like the same things, since they are usually trend-oriented. If you can interview five of them, you have the best source you could get. It is like interviewing a band about being on stage rather than interviewing their manager: which do you think is a more reliable source?
The alternative "A research report by a credit card company detailing purchases of teens between 2010 and 2014" must be ruled out, since it limits the subject to purchases made with credit cards, and not every teenager has got one.
