Answer:
The best answer to the question: Which idea from the passage is really an opinion, would be: "I felt that I breathed an atmosphere of sorrow."
Step-by-step explanation:
"The Fall of the House of Usher" is a short story by American writer Edgar Allan Poe, and which was first published in 1839. In this particular excerpt, most of the narration is actual fact, the speaker is simply describing what he sees, and what is there, but there is a point, near the end, where the speaker goes from what he sees and feels from the actual scenery, into what he thinks those visible things mean. Thus, he states something that he feels, or senses from what he sees and believes that all of it conveys sorrow. This is why that particular line in the excerpt is the correct answer to the question. The expression: "I felt..." strays from actual fact and goes into the perception of the one describing what he is seeing.