The correct answer should be Both of these answers
Onomatopoeia is imitating animal sounds in verbal form, that is, writing things like bark or meow. In poems, onomatopoeia can create musical effect if made to rhyme or has an assonance (like moo moo in old macdonald had a farm). It can also make it more effective if it's some ominous sounds like growling or hissing or similar.
