Read the excerpt from "Ghost House." The whippoorwill is coming to shout
And hush and cluck and flutter about

The most likely reason Frost includes assonance in these lines is

to point out important ideas in the first line.
to create pleasing sounds in the second line.
to place emphasis on the word “shout” in the first line.
to link “coming” in the first line with “cluck” in the second line.