The correct answer is D. Should contain no more than 50 characters derived from the paper title.
Step-by-step explanation:
According to APA style manual which is one of the writing manuals used in formal and academic writing, each page of a paper needs to have on the top of it a header or running head and the page number. In this way the header is placed on the upper left of the page, needs to include maximum 50 characters and it is derived from the paper title, usually by including the most important words or concepts on it. On the other hand, the numbers are placed on the upper right of the page and usually begin on the first page. Thus, the statement that is true about the title in the header is option D.