I can't see the examples. But assonance means a resemblance in the sounds of words or syllables either between their vowels (e.g., meat, bean) or between their consonants (e.g., keep, cape).
Answer:
A. Warned
Explanation: When you give a warning it means that something very dangerous could happen.
The narrator is invited to dinner as an anniversary of sorts that happened a long time ago, where he announced that he built a time machine. And then he arrives dirty and rugged beginning to tell the guests his story