I believe the best answer to be indeed letter B. Being able to see moisture implies the fog is quite dense.
Explanation:
The excerpt makes a point of describing the fog. It is as if the author wants the audience to picture it in a vivid and almost exaggerated manner. For readers to understand how incredibly foggy it was, the author says moisture was "so thick you could almost see it sparking in the dim sunlight". In the next sentence, he even says, "it seemed there was more water in the air than in the bay". He employs these descriptions as imagery, appealing to readers' sense of sight so that they will have a clear image of the fog in their minds.
The correct answer is (B)”Being able to see moisture implies the fog is quite dense.” The writer states that it is possible to see the moisture in the dim sunlight because it is too thick .
