Final answer:
Option A, 'Seemingly safe things chewed by pets result in disaster,' best varies the sentence structure of the paragraph by focusing on the objects and effects before mentioning 'pets,' thereby avoiding the repetition of starting sentences with 'Pets.'
Step-by-step explanation:
The student is asking which revised sentence best varies the structure of the first paragraph, specifically targeting variation away from sentences starting with the word 'Pets.' The best option among the provided choices is A, which states: "Seemingly safe things chewed by pets result in disaster." This revision rephrases the sentence in a way that focuses on the objects first ('seemingly safe things') and then presents the subject ('pets'), thereby varying the sentence structure effectively. Options B, C, and D either start with 'pets' or are less concise and clear in varying the paragraph structure.