A Woman Who Is 16 Weeks Pregnant Asks the Nurse,"Is

A woman who is 16 weeks pregnant asks the nurse,"Is it possible to tell by ultrasound if the baby is a boy or girl yet?" What is the best answer?

A) "A baby's sex is determined as soon as conception occurs."
B) "The baby has developed enough to enable us to determine the sex by examining the genitals through an ultrasound scan."
C) "Boys and girls look alike until approximately 20 weeks after conception,and then they begin to look different."
D) "It might be possible to determine your baby's sex,but the external organs look very similar right now."