Concept:Gamete, egg, and ovum all refer to reproductive cells, while embryo is the early developmental stage after fertilization.
Explanation:Gamete is a general term for a sex cell (sperm or egg).
Egg and ovum are the same – the female reproductive cell.
Embryo is formed after the egg (ovum) fuses with sperm and begins to develop.
Thus, embryo is at a different, later stage compared to the other three.
Hence, embryo is the odd one out.
Answer:B. Embryo
