The correct answer would be the third one.
"It would benefit many people to learn how to help protect our environment."
It has a professional tones and uses grammatically correct words.
I hope this helped!
epigram<span>a : pithy saying or remark expressing an idea in a clever and amusing way</span>
The correct answer would be A. The first step in getting the gist would be to identify the keywords. Getting gist is the same as knowing the main idea of a certain passage. The very first to identify this should be to find keywords that you think is important in the text and speaks of the message of the passage.
C. Thomas Paine is the correct answer