Which layer of the uterus is responsible for parturition?

Given below are two statements: One is labelled as Assertion $A$ and the other is labelled as Reason $R$ :
Assertion $A$ : Breast-feeding during the initial period of infant growth is recommended by doctors for bringing up a healthy baby.
Reason $R$ : Colostrum contains several antibodies absolutely essential to develop resistance in the newborn baby.
In the light of the above statements,choose the most appropriate answer from the options given below:

What is meant by parturition? Describe the changes occurring in the uterus during this period.

Production,secretion and ejection of milk requires the synergistic effects of prolactin and

The signals for parturition originate from which of the following?

Active mammary glands are $....$ in structure.