Final answer:
Francesca followed the melodic sound down the stairs and discovered Roy at the piano, making c) the correct answer.
Step-by-step explanation:
Francesca followed the melodic sound and found Roy at the piano. Therefore, the correct answer is that c) Francesca followed the melodic sound and found Roy at the piano. This type of activity, where a character is drawn to a sound and discovers its source, is common in literature as it can be used to drive the narrative forward, develop characters or create a certain ambiance. For example, similar instances occur when a character is lured by music or sounds in various scenes across literature and film, indicative of curiosity or a narrative segue to a significant plot development.