The correct answer is B. The details in the passage suggest Aubrey and Flo share a longstanding and comfortable relationship characterized by a deep familiarity and understanding.
Based on the provided passages, the reader can infer that B. Aubrey and Flo have been friends for a long time. The description of their time together without friction for three years suggests a longstanding and comfortable relationship. Moreover, the detail that Flo did most of his reading and that she opposed his dominance with indifference also hints at a deep familiarity and understanding that typically comes from a long-term friendship. From the passage, the reader can tell that Aubrey and Flo have been friends for a long time.
This can be inferred from the passage where the narrator mentions Flo's least favorite pastime is writing her own poetry. The passage does not provide any information about Flo's intelligence or her ability to meet guys. However, it does mention that Flo is a musician and has some beautiful notes in her voice.