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
The indifferent embryo begins phenotypic sexual differentiation during 
Select and explain. 
A. Week 3 of development, B. Week 5 of development, C. Week 7 of development, D. Week 12 of development
C: Week 7 of development
Answer: C: Week 7 of development 
Explanation: The embryo during weeks 1-6 remains in an undifferentiated stage. The embryo begins phenotypic sexual differentiation during week 7.