This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
Implantation occurs in which stage: 
Select and explain. 
A. Morula, B. Zygote, C. Blastocyst, D. Blastomeres
C: Blastocyst
Answer: C: Blastocyst 
Explanation: Ans. C i.e. BlastocystImplanatationImplantation is the very early stage of pregnancy at which the embryo adheres to the wall of theuterus.At this stage of prenatal development, the embryo is a blastocyst.It is by this adhesion that the fetus receives oxygen and nutrients from the mother to be able to grow.In humans, implantation of a feilized ovum is most likely to occur about 9 days after ovulation, ranging between 6 to 12 days