The answer choice which best explains how affixes change the word cacophonous to another part of speech is; Replacing the suffix -ous with the suffix -y creates the noun cacophony.
Although, affixes are subdivided into prefixes and suffixes, both constitute a group of letters used to change the meaning of words.
Hence, as evident in the word given; cacophonous, the word is in it's adjectival form.
However, replacing the suffix -ous with the suffix -y creates the noun; cacophony.
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