The most effective question for William to ask is:
A research question is an inquiry that informs an in-depth study of a matter.
If the USDA's recommendation about the consumption of dairy products is different from what is currently obtainable, then it will be wise to find out where the USDA sources its guidelines.
Option B offers a good research question to solve the matter.
Learn more about research questions here:
https://brainly.com/question/1442162
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