Final answer:
Scott Joplin's most famous composition is a. "The Maple Leaf Rag."
Step-by-step explanation:
a. The Maple Leaf Rag is Scott Joplin's most famous composition. It was his first successful composition and played a significant role in popularizing ragtime music as a uniquely American genre.
Joplin, an African American composer, was known as one of the great innovators of ragtime music.