Which Statement Represents the Principal Difference Between the Uterine Cycle

Which statement represents the principal difference between the uterine cycle of humans and the cycles of other mammals?

A) The uterine cycles of other mammals occur if fertilization occurs, whereas the uterine cycle of humans occurs if fertilization does not occur.
B) The uterine cycle of humans occurs if fertilization occurs, whereas the uterine cycles of most mammals occur if fertilization does not occur.
C) The uterine cycles of most other mammals lack menstruation.
D) The uterine cycles of most other mammals do not involve any changes to the uterine lining.
E) Peaks of progesterone in the uterine cycles of most other mammals correspond to periods of enhanced sexual receptivity referred to as estrus or "heat."