Final answer:
Rukmani uses a flushing toilet for the first time at the doctor's house. This reflects the theme of encountering modern conveniences in literature and is connected to the successful innovations of the era such as sewing machines, movies with sound, and typewriters.
Step-by-step explanation:
At the doctor's house, Rukmani uses a flushing toilet for the first time in her life. This question relates to a scene from a work of literature, where a character encounters modern conveniences that were not commonly accessible to everyone, especially in rural areas or past eras. The introduction of such modern amenities was part of the broader industrial and technological advancements of the era.
Inventions like high-powered sewing machines, movies with sound, and typewriters were successful innovations of their time. However, it is worth noting that frozen foods, while an existing concept, were not as immediately successful or widespread in adoption as the other options listed. Therefore, to answer the question, Rukmani uses a flushing toilet.