Which One of the Following Is the Best Example of a Covert

Which one of the following is the best example of a covert rather than overt) strategy that one might use while studying a textbook chapter?

A) Using chapter headings and subheadings to make a rough outline of the chapter
B) Working hard to keep one's mind from wandering while reading the chapter
C) Using self-stick notes to mark sections that are hard to understand
D) Writing a summary of the key ideas in the chapter