What is the advantage of marking up a book according to the speaker?

A、Markingupabookhelpsreaderstakeinthebrilliantideasinthebook.
B、Markingupabookenablesreaderstoknowwhattheyread.
C、Markingupabookmakesreadersfeelliketheownerofthebook.
D、Markingupabookmakesreadersconsciousofthefactthattheyarereadingactively.