This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous (Gynae), Subject name: Gynaecology & Obstetrics
Expected date of delivery is calculated by all EXCEPT 
Select and explain. 
A. Nine calender months plus 7 days, B. 280 days or 40 weeks, C. 266 days or 38 weaks, D. 10 lunar months
C: 266 days or 38 weaks
Answer: C: 266 days or 38 weaks 
Explanation: [Cl (266 days or 38 days) (64 - Dutta 6th)Duration of Pregnancy - Calculated by clinicians in terms of 10 lunnar months or 9 calender months and 7days or 280 days or 40 weeks, calculated from the first day of the last menstrual period. This is called menstrual age**True gestation period is to be calculated by substracting 14 days from 280 days i.e. 266 day. This is called fertilization or ovulatory age