The author's argument that a poor diet can be harmful to a person's health is effective because it includes facts from a credible source, as stated in option D.
A source is the material from where we obtain the information used to support our claim or argument. A credible source is a source that has credibility, that can be trusted, because it is known for being serious and ethical.
In the passage we are analyzing here, the author uses facts from a credible source, the Centers for Disease Control and Prevention, to support the argument presented.
With the information above in mind, we can choose option D as the correct answer.
The complete question with the answer choices is the following:
The author's argument that a poor diet can be harmful to a person's health is
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