Final answer:
The irony in the passage from "To Build a Fire" where the dog senses the man's death and heads to the camp is option 2: situational irony, as it contrasts the expectation of the man's knowledge with the dog's instinctive wisdom.
Step-by-step explanation:
The passage from "To Build a Fire" presents a scenario where the dog senses the death of the man and decides to move on to the camp it knew. The irony in this situation is Option 2: Situational Irony, because it contrasts the reader's expectation that the man, being human and presumably intelligent, would know the right way to survive, whereas it is the dog who knew the correct path all along.
This is ironic because the man's presumed superiority in reasoning is undermined by the instinctive wisdom of the dog. We're also presented with a scenario where human tools and knowledge fail against nature's unforgiving elements, further adding depth to the situational irony.