Which of the Following Processes is Unique to Humans

Question

Which of the following processes is unique to humans?
A) placental development
B) fertilization
C) internal development of the embryo
D) menstruation

Accepted Answer

Menstruation is unique to humans among the options listed. While other mammals have cycles related to reproduction, the specific process of menstruation, involving the shedding of the uterine lining, is distinct to humans and a few other species, but not broadly shared across the animal kingdom like placental development, fertilization, and internal development of the embryo.