C- The proper use of a citation format such as MLA can help you avoid plagiarism. Parenthetical citations within the text of your paper let your reader know when you've used information from another source. The parenthetical citation corresponds to a source listed on your works cited page.
I think the best word to describe this sentence would be toot.
Answer: I believe it’s A.
Explanation: it explains difficulties that astronauts may face and in the following sentence it goes more in depth