This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Embryology, Subject name: Anatomy
[{'content': 'Gastrulation occurs at which week of gestation: \nSelect and explain. \nA. 1 week, B. 5 week, C. 3 week, D. 10 week', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. C. 3 weekThe gastrulation is the most characteristic event occurring during the third week of gestation because it forms the three germ layers that form all the tissues and organs of the body. The process of formation of three germ layers is called gastrulation.', 'role': 'assistant'}]