At Her First Prenatal Visit, a Woman Is Discussing Fetal

At her first prenatal visit, a woman is discussing fetal development with the nurse. The patient asks, "When will my baby actually have a heartbeat?" The nurse should reply, "The heartbeat of an embryo is distinguishable by:

A) "The fourth week."
B) "The sixth week."
C) "The eighth week."
D) "The twelfth week."