The sentence that is NOT an allusion is:
"He was as hungry as a horse."
This sentence uses a simile rather than referencing a specific historical, literary, or cultural figure or event, which would be an allusion. The other sentences include references to "rabbit hole" from "Alice in Wonderland," "kryptonite" from Superman, and "Eden" from the biblical story of the Garden of Eden, all of which are examples of allusion.