Yes it is because no one knows and you don't expect to get the answer.
The answer is D, because it is a known fact that is it mandatory for children to go to school.
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.