Answer:
The sentences with the best language to insert in an informative essay include:
A. Heroes come in many varieties, but they all share certain qualities;
C. Firefighters are heroes because they risk their lives to help others; and
F. Some people think heroes need to be famous, but that is not true.
Explanation:
Notice that all the options selected are written in formal langugage.
When writing an informative essay, it's best to maintain the use of a formal academic writing style instead of being very personal and or relying on personal experience.
Notice for instance that sentence 'B' uses informal English grammar because it reads "Here's what I'm gonna..." instead of "Here's what I'm going to..."
Sentence 'E' also contains the use of informal grammar. It reads "Athletes aren't heroes 'cuz..." Instead of "Athletes aren't heroes because...."
Sentence D in referring to a personal preference (that is "I look up to Ms. Sanchez) breaks the rule of informative essays
Cheers!
