Question

What is this allusion referring to? "He was so strong, I expected him to tear off his shirt and reveal an "S" on his chest."

Answer 1

pop culture.

It's referencing Superman.

You could argue that Superman stems from a body of famous literary work (that is, the source comics), but that's probably not what they're looking for. As Superman is best known from a combination of comics, cinema, TV and merchandise, it's basically a pop culture reference.

Answer 2

Answer: B) Pop culture.

Explanation: allusion is a literary device that consists in making a brief reference to a person, an event (historical, political, cultural, etc), or a place. In the given sentence, we can see an example of an allusion to pop culture (corresponding to option B), specifically the speaker is referring to Superman (tear off his shirt and reveal an "S" on his chest), which is a symbol of pop culture.