The correct answer is allusion.
Allusion means a brief and indirect reference to a person, place, thing or idea of historical, political or literary significance. Allusion does not describe in detail the person or thing it refers to, the reference is general, like a passing comment.
The reader is expected to have enough knowledge to spot and understand the allusion.
In the above example, Michelangelo is used as an allusion, it is merely a reference to a famous person without any hidden meaning.