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.
D, for you want your topic to interest and hook your readers. It helps narrow down your choices and creates the most effective way to relay your information
Answer:
Digital currency has to be regulated. Digital currency has to be accepted by domestic and foreign banks. Digital currency has to be protected and secured by FDIC.
He umbrella<span> is a symbol of what she wants to be and to have as a young Chinese American girl. </span>
