Which of the Following Statements About the Timing of Effects

Which of the following statements about the timing of effects of teratogens is true?

A) The sensitive period for the development of the external genitalia occurs prior to the sensitive period for the heart.
B) The sensitive periods for the central nervous system and the heart are the same.
C) Exposure to teratogens during the fetal period is likely to lead to major structural defects.
D) All of the statements are true.
E) None of the statements is true.