A teratogen is a(n)

A) fertilized egg that undergoes rapid cell division.
B) unborn child with one or more physical defects or abnormalities.
C) chromosomal abnormality.
D) substance that can cross the placental barrier and harm an unborn child.

Teratogen

is any substance or agent that can cause congenital anomalies or increase the incidence of an anomaly in a population.

Placental Barrier

Refers to the cellular and structural barrier formed by the placenta, which separates the mother's blood from the fetus's blood, allowing exchange of nutrients and waste while protecting the fetus from harmful substances.

Unborn Child

A developing fetus or embryo that has not yet been born, typically in the context of pregnancy.