The author suggests in this excerpt that <u>it is important for people to be informed about what their bodies need</u>.
Explanation:
In the given excerpt from "Healthy Eating," the example of 55-year-old Juanita Ferguson provides one key aspect of careful eating habits. Added to that, she had undergone a kidney transplant which further complicates things.
When the author says <em>"it was the finer points"</em> that Ferguson was missing, it means that those small 'breaks' such as skipping meals on busy days, or consuming the wrong products play a huge role in the maintaining of her health. The suggestion in this excerpt is that <u>it is important for people to be informed and knowledgeable about the needs of their respective bodies.
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Thus, the correct answer is the fourth/last option.