Answer:
In uterus.
Step-by-step explanation:
Implantation can be defined as a stage of pregnancy during which the embryo reaches to uterus and gets attached to the uterine wall, known as endometrium.
The embryo at this stage is known as blastocyst. Due to this attachment, embryo gets nutrients and oxygen from the mother required for growth.
Thus, the correct answer is uterus.