Question

multiple choice question
what usually occurs about seven days after fertilization?
implantation
formation of morula
differentiation
formation of mature placenta

Explanation:

After fertilization, the blastocyst usually implants in the uterine lining about seven days later. The morula forms earlier (around 3 - 4 days after fertilization). Differentiation is a more general and ongoing process in development. The mature placenta forms much later in pregnancy.

Answer:

Implantation