Mel Is at the Obstetrician's Office with His Girlfriend Denise

Multiple Choice

Mel is at the obstetrician's office with his girlfriend Denise, who is pregnant with their child. They have just started the ninth week of the pregnancy, and the doctor explains to them that the unborn child's brain has developed distinct structures and is already beginning to regulate certain body functions. Based on what you know about prenatal development, you know that the period of the ____ has just begun.

A) ​zygote
B) ​embryo
C) ​umbilicus
D) ​fetus