The best answer choice that explains how the repeated phrase "Napoleon is always right" is used rhetorically in Chapter 9 of Animal Farm is:
4. The author uses the repeated phrase "Napoleon is always right" as a rhetorical device to illustrate how propaganda is employed to build unquestioned loyalty among the animals, encouraging them to accept Napoleon's authority without critical thinking.
This choice accurately reflects the way propaganda is used in the novel to manipulate the animals' perception of leadership and discourage dissent or critical thought regarding Napoleon's decisions. The repetition of the phrase serves to reinforce a blind loyalty, highlighting the theme of control through propaganda.