Explanation: It is not essential. Scoring well on an AP exam requires studying, yes, but not memorization of a book. Instead, focus on understanding the concepts overall and studying key points of each unit. What book you use for that is not essential, as long as it is decently up to date.
I'm assuming you need the ramp which will make it the easiest which would be the 6m ramp because since it is longer it will be a more gradual incline making it easier to move the boxes.
