Answer: It is important to write down your ideas so you don't forget them, and also so that you can re-read them again later, to make sure you aren't missing anything. It's also a nice thing to have to base your paragraphs off of, one idea/discovery for each paragraph. It helps space it out and also organizes.
The answer to this question is would be B.
I love this book!
But I am not sure what you mean with your question (it's missing a verb).
But if you're looking for more information: The sense of guilt in this book is often created by other characters, when they're trying to come to terms with some tragedy (such as many characters being blamed for Sophie Mol's death). So in a way, guilt can function as an explanation. But also it's created by the social norms (as when Estha feels guilty because of the Orangedrink man).