Which of the following statements is true of teratogens?

A) They exclude substances ingested by mother, such as nicotine or alcohol.
B) The effects of chemical teratogens depend on the timing of exposure.
C) They refer to the birth defect caused by radiation.
D) The development of a fetus is typically enhanced by teratogens.

Teratogens

Agents, such as chemicals or viruses, that can cause congenital anomalies or developmental disorders in a developing fetus.

Birth Defect

A physical or biochemical abnormality that is present at birth and may cause physical or mental disabilities.

Chemical Teratogens

Substances that can cause birth defects or developmental malformations when exposed to a fetus during pregnancy.