B. A feeling of having experienced something before
Read Explanation:
Déjà vu is a French term meaning “already seen.” It refers to the strange feeling that a present situation has happened or been experienced before, even though it is actually new.
A sudden fear → ❌ This is not déjà vu.
A feeling of having experienced something before → ✅ Correct.
A forgotten memory → ❌ A forgotten memory is not necessarily déjà vu.
A dreamlike illusion → ❌ Not the exact meaning of déjà vu.