Answer:
The answer is indeed letter A. a repetition of one or two lines used as refrain.
Explanation:
The poem "Do not go gentle into that good night", by Dylan Thomas (1914-1953), is a villanelle. That means it presents five tercets followed by a quatrain; also the rhyming scheme for those lines is: aba, aba, aba, aba, aba, abaa. This poem has two refrains. Refrains are repeated lines that appear as a means of dividing the poem into sections. The refrains are the bolded lines in the excerpt below:
Do not go gentle into that good night,
Old age should burn and rave at close of day;
Rage, rage against the dying of the light.
Though wise men at their end know dark is right,
Because their words had forked no lightning they
Do not go gentle into that good night.
Good men, the last wave by, crying how bright
Their frail deeds might have danced in a green bay,
Rage, rage against the dying of the light.
