contestada

What is the effect of the refrain in the poem?
A) It serves as a catchy line that is easily remembered by those who read the poem.
B) It gradually increases the intensity for the narrator as it includes the only response the raven gives him.
C) Its repetition at the end of each stanza takes on more meaning until the end when it changes slightly.
D) It summarizes the events that have happened to the narrator in the previous stanzas in the poem.