At the End of Pregnancy,the Uterus Becomes Responsive to Stimuli

Multiple Choice

At the end of pregnancy,the uterus becomes responsive to stimuli to which it was previously refractory because

A) Plasma progesterone levels fall while the levels of estrogen continue to rise
B) The ratio of progesterone to estrogen decreases
C) The myometrium has reached the limits of its distensibility
D) All of the choices are correct
E) None of the choices are correct