The answer is A. how do the parts of the text relate to the whole?
It is important to know the author's purpose because knowing the author's purpose can change how the story is being told. If someone said,"Mom, I would really like this new video game for my birthday." and the author's purpose was to inform, it would be informing the mom that the person wanted the video game. If the author's purpose was to persuade, that person would be persuading the mom to get him the video game.
I believe the answer is B. instrument for weighing.
Please correct me if I'm wrong!! :)