Answer:
A. to comment about an issue facing society is the correct answer.
Explanation:
In literature, a theme is defined as the main idea or the meaning behind the work. Theme can be literally mentioned or just inferred by readers. It is different from the <em>subject</em>, which is the topic of the work.
Letter B is incorrect because the one who explores creativity is the author at the moment of writing.
Letter C is also incorrect because not all themes are related to the author's life.
D is also incorrect because elements of surprise and mystery are not the only that could be introduced by choosing a particular theme.
This way, letter A is correct; based on the definition, any theme can be chosen as long as the subject is helpful to do so.