Answer the following question given this paragraph: 

Within seconds of birth, the umbilical cord is cut. Without this connection to the placenta, the baby can’t exchange gases, so carbon dioxide quickly builds up in the baby’s blood. This stimulates the baby’s brain to trigger breathing, and the newborn takes her first breath.


Q: What structure connects the fetus to the placenta, allowing the exchange of gases?

 Choices:

- sediment cord

- skin cord

- belly button

- umbilical cord

A:
umbilical cord
