Final answer:
Orwell uses verbal irony in the passage through Squealer, who insinuates that Napoleon is dying when, in fact, this is not meant to be taken literally.
Step-by-step explanation:
The statement that best explains Orwell’s use of irony in the passage is Squealer uses verbal irony because he does not mean that Napoleon is really dying. This instance is one of verbal irony where the character Squealer says something that is not expected to be taken at face value, implying the opposite of what is said. It contrasts with the expectation that Squealer, as Napoleon’s mouthpiece, would communicate genuine news about Napoleon's health status to the other animals.