Which literary device emphasizes a contradiction between what is expected and what actually occurs?

The correct answer is the literary device that highlights the contrast between what is anticipated and what truly transpires, which is known as irony. Irony can manifest in various forms, including verbal irony, situational irony, and dramatic irony. This device often creates a sense of surprise or humor, engaging the audience by presenting scenarios that defy their expectations. For example, if a fire station burns down, the outcome is contrary to what one would expect, thus illustrating situational irony.

In contrast, simile involves comparing two different things using "like" or "as," which does not create a contradiction but rather a vivid likeness. Hyperbole refers to exaggerated statements not meant to be taken literally for emphasis or effect, rather than focusing on incongruities in expectations versus reality. Colloquialism pertains to informal language or expressions used in everyday conversation, which also does not involve contradictions in expectation. Therefore, irony specifically centers on that tension between expectation and reality, making it the most fitting choice in this context.