Which mechanism 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:

Following features are seen during the dilation stage of parturition $EXCEPT$ . . . . . . .

Under the influence of oxytocin,which layer of the uterus exhibits strong contractions during parturition?

Explain the process of lactation.

Which of the following contains $IgA$ antibodies?