What is the most effective way to revise sentence 32?
(32) In late spring, the sides of the cliffs echo with the music that is the music of tiny tree frogs. THIS IS THE SENTENCE

In late spring the sides of the cliffs echo with the music of tiny tree frogs.

In late spring the sides of the cliffs echo with the music of tiny tree frogs, and it is music.

In late spring the sides of the cliffs echo with the musical echoes of tiny tree frogs.

In late spring the sides of the cliffs echo music, and it is the music of tiny tree frogs.