A school-wide survey by the cafeteria is the best source that best defends the assertion about the fast food and sugary foods consumed by the school students. Thus, option a is correct.
Sources are the places and people that can provide the information and facts about something and act as evidence to support the claim. Articles, surveys, interviews, etc., are examples of sources.
A survey conducted in the high school by the cafeteria is the best source as the survey includes many people and the information to conclude the result will be more accurate compared to an interview of a single person, or an article interviewed with three students.
Therefore, a school survey is the best source.
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