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
Foldings of embryo occurs at:- 
Select and explain. 
A. 3rd week, B. 4th week, C. 5th week, D. 6th week
A: 3rd week
Answer: A: 3rd week 
Explanation: At the end of 3rd week the embryonic area shows the development of head fold, tail fold and two lateral folds. These folds conve the flattened germ disc to cylindrical embryo.