Even being a visual learner the trick is to take notes, even if you never look at the notes ever again its good to write them down, you are more likely to remember something you have written down rather than to just look at it. Science is something that could be easy, you just have to take it at your own pace, don't try to learn science by giving it a quick read or glance at it.
The answer is D. With mechanical advantage, less work is put in for a better result. It can apply force in a shorter distance, but increase distance itself.