The structure that surrounds the yolk and transports nutrients to the embryo is the yolk sac.

Here's why:

* Yolk: This is the nutrient-rich food source for the developing embryo.

* Yolk Sac: A membrane-like sac that encloses the yolk. It has blood vessels that absorb nutrients from the yolk and transport them to the developing embryo via the umbilical cord.

Let me know if you have any other questions!