What is a musical scale of four notes, bounded by the interval of a perfect fourth?

Which indian dance form originated from dance-dramas based on the life of lord krishna? a: odissi b: kathak c: manipuri d: bharata natyam

What is the term for a recurrent musical section between various contrasting sections? a. concerto grosso b. basso ostinato c. fugue d. ritornello

In a paragraph of no less than 125 words, explain the single most important factor involved in advancing american classical music in the twentieth century.