The purpose of this passage is to clarify what a UFO is. The passage tells you that even though UFOs often star in science fiction movies, most UFOs are actually aircraft, kites, clouds, meteors or rocket debris. It also cites a famous case in order to provide evidence for their claim.
We need to make sure we know what each of these words mean before we can decide which answer is best.
Satire is the use of humor, comedy, or exaggeration to criticize people's vices.
Irony is expressing your meaning by using language that is the opposite of what you mean, usually for humorous effect.
Dialect is a particular form of language that is specific to a region or group.
Hyperbole is extreme exaggeration.
With these definitions in mind, we can knock hyperbole off immediately as there is nothing exaggerated about the words we're looking at. Satire doesn't quite fit either because it's not obvious or apparent what is being satirized here. Irony also isn't a good choice because what is ironic isn't immediately obvious. Dialect is your best choice because the last part--"a-comin"--implies someone has dropped the g at the end of coming and makes it sound like a dialect.
So that things would be clearer
