The main thing that this question is asking is which sentence does not have a formal tone. A formal tone for research writing usually means using more professional (instead of casual, everyday) language and free of your own opinions.
This means choice D is inappropriate because it is opinionated. Using "I think" is not formal tone.
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Answer: D) I think one of the most frustrating things about owning a cat is that they don't obey many commands.
Adverbs are known to describe how an action is being done. Some popular adverbs would be carefully, correctly, eagerly, easily, fast, loudly, patiently, quickly, and quietly.
Romeo's reason for going into Juliet's tomb was to take the ring off and see her one more time.
Answer: In formal language, grammar is more complex and sentences are generally longer. For example: We regret to inform you that the delivery will be delayed due to adverse weather conditions [formal] Sorry, but the delivery will be late because of the weather [informal]
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