B. skeptical of Usher's theory.
In the excerpt the narrator is listening to Roderick Usher talk about what he thinks is molding "the destinies of his family". Usher says that the evidence is still yet to be seen. While the narrator does not outright dismiss Usher's theorizing, he also doesn't give any indication that he agrees with it. The narrator says, "such opinions need no comment, and I will make none." Basically, since the narrator has nothing to say on the matter because he's not quite sure, he's just going to keep quiet. It's obvious the narrator's thoughts or questions would not be of interest to Usher anyways.