Answer:
Hi!
The answer to the question would be option B. Formal
Step-by-step explanation:
Based on the excerpt provided, it seems that Ryo and Tsuruishi's relationship could be friendly, comfortable and respectful.
To start, both characters are being respectful yet comfortable with each other. This can be seen Tsuruishi's asks Ryo to put the tea into the kettle and he playfully declines it because it's too expensive, yet she ignores him any way and does it. This conveys that she feels comfortable enough to do that. Moreover, the author emphasizes that they both are smiling, which conveys that they have a friendly relationship. Overall, their relationship, based on this ecxerpt, seems everything but formal, so therefore the answer would be B.