A primary source usually does not include poor spelling because the creators want the source to be credible and reliable.
Part A
Helen Keller's word choice in her description of her lessons with her teacher help to reveal that she is a very detail-oriented person. Being blind and deaf, she only had the sense of touch, smell, and taste, all of which are not very easy to receive information through. The way Helen Keller was able to describe the world around her was with the feelings and the smells of the earth, and this tells us how happy she is to pay her mind to these details. (I wrote this without knowing it was multiple choice, but yeah the answer is B.)
Part B
The word choice in the second and third paragraphs help to develop the idea presented in Part A? The answer is C.