I believe the correct answer is to help the reader visualize a view where water and sky are difficult to tell apart.
The author is trying to portray an image where the water and the sky are somehow blending into each other - you can't tell where one ends and the other one begins, because both items are colored similarly - various shades of blue.
Answer:
Imagination overcomes reason when the desire or need for something to be true, or the fear that something is true, is stronger than the persuasive power of logic and observation.
The answer to this question would be C. informal
Hope This Helps.......... Have A Nice Daaaay!