Should you use an X or a check mark when filling out a job application?

Here is the standard: if the blank you are completing is in the shape of a box, a check mark is the most appropriate way to fill it; if the blank you are completing is in the shape of a line (fill in the blank line), the correct way to reply is with a check mark. You can correlate to these that the best way to complete a question with ovals for your response is to completely fill, or darken, the oval that corresponds with your answer.