When a fossil disappears from the fossil record, we know that those organisms went extinct.
Explanation:
The first option is not correct because there simply isn't any proof of alien abductions, nor that they have visited our planet.
The second option is correct because when a fossil that has been present in particular geological layers suddenly is missing, usually means that the organism went extinct at that time or very soon after.
The third option is not correct because the fossils are proof of the existence of the organism.
The fourth option is not correct because one of the options above is correct.
