When doctors discuss prenatal development, they often calculate the due date from the first day of menstruation. In fact, the baby’s gestational age is calculated from the first day of menstruation. At a maternity clinic, an obstetrician mentions that when a woman is 10 weeks pregnant, the baby is referred to as a fetus. Which of the following is the correct calculation of the baby’s age from the moment of fertilization, assuming a 28-day ovarian cycle?Select one:

#9. Which mechanism prevents an ovum from being fertilized by multiple sperm cells?Select one:

Stages in Fetal development: 

1. First trimester

2. second trimester 

3. third trimester

Match four of the fetal developments listed below with the appropriate trimester numbered above. 

 my asnwer for this is 2,3,3,1. is this correct?  Please let me know, whenever you get a chance to. Thank you :)

Which of the following rows correctly completes the following sentence?

______A_____ occurs during fetal development when an embryo is not exposed to adequate levels of ____B___ _______ during neurulation.

Select one: a). A: Microcephaly B: Zika virus. b). A:Anencephaly B:Folic acid. c).A:Spina bifida B: Vitamin B12. d). A:Malformation of the limbs B:Thalidomide. I think it's c but im not sure