Fog rolling down the river is a form of figurative language known as personification. Personification occurs when a non-human object is given a human characteristic or action. In this case, fog cannot literally "roll" down the river. I mean, just imagine a person rolling down a hill like a derp-head. Fog doesn't do that, but in a figurative way, it "rolls" down the river. I hope you can understand :')
I would go with B, I do not for sure know the answer but that is the one that seems to make the most sense
The main clame is well its hard to tell i guess it s trying to understand how her grandfather had such a hard time growing up
J.K. Rowling is the author of Harry Potter
(that's what she is known for)
hope this helps