What are the questions ? I just did that short story
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.
<span>Assuming that this is referring to the same list of options that was posted before with this question, this would most likely occur in the middle of the plot to add suspense. </span>