The Pregnant Patient Who Is at 14 Weeks' Gestation Asks

The pregnant patient who is at 14 weeks' gestation asks the nurse why the doctor used to call her baby an embryo, and now calls it a fetus. What is the best answer to this question?

A) "A fetus is the term used from the ninth week of gestation and onward."
B) "We call a baby a fetus when it is larger than an embryo."
C) "An embryo is a baby from conception until the eighth week."
D) "The official term for a baby in utero is really zygote."