This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Development period- week 1,2,3,4, Subject name: Anatomy
Very often the first indication a woman has that she is pregnant is a missed menstrual period. In which week of embryonic development will a woman experience her first missed menstrual period? 
Select and explain. 
A. Sta of week 3, B. Sta of week 4, C. Sta of week 5, D. Sta of week 6
A: Sta of week 3
Answer: A: Sta of week 3 
Explanation: Feilization of ovum takes place on day-15 of menstrual cycle. woman notices missing of next menstrual period from day1- day5 if implantation takes place. That day corresponds to sta of 3rd week of embryonic development ( day15-day28-day1-5 of next cycle= >14 days)