Question

the placenta
the vagina
the heart valve
the umbilical cord
elle
jordan

Explanation:

In fetal development, the umbilical cord is the structure that transports oxygen (and nutrients) from the placenta to the fetus. The placenta facilitates exchange but the umbilical cord is the direct connection for oxygen delivery to the fetus. The vagina is a birth canal, and the heart valve is part of the fetal heart, not for oxygen transport to the fetus.

Answer:

The umbilical cord