This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
Ossification of long bones begins at what age? 
Select and explain. 
A. 3rd week of gestation, B. 7th week of gestation, C. 5th week of gestation, D. 9th week of gestation
B: 7th week of gestation
Answer: B: 7th week of gestation 
Explanation: Ossification in the long bones begins by the end of the 7th week of gestation with shaft of femur Ref: Gray's39e/p125-150