This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Gynaecology & Obstetrics
The first trimester completes by 
Select and explain. 
A. 12 completed weeks, B. 13 completed weeks, C. 14 completed weeks, D. 16 completed weeks
C: 14 completed weeks
Answer: C: 14 completed weeks 
Explanation: Historically, the first trimester extends through completion of 14 weeks, the second through 28 weeks, and the third includes the 29th through 42nd weeks of pregnancy. Thus, there are three periods of 14 weeks each. (Ref: William's Obstetrics; 25th edition)