Question

which of the following is a common purpose of literary authors?
to persuade a government to change a law
to teach a specific school subject
to explain a process for doing something
to express a message (theme) about human nature

Explanation:

Literary authors often use their works to convey themes or messages, especially about human nature, emotions, or experiences. Persuading governments to change laws is more related to political or advocacy writing, teaching a school subject is educational writing, and explaining a process is technical or expository writing. Literary works (fiction, poetry, etc.) typically aim to express thematic ideas about human nature.

Answer:

to express a message (theme) about human nature