Answer:
D. Reflex action triggered by nursing
Explanation:
Milk let-down
During the process of feeding the baby , the baby sucks the breast , which triggers the nerves present in the nipples .
The nerves then releases the hormones into the bloodstream of the mother .
The homones released are the prolactine , which helps in the milk - making tissues .
And the other hormone released is the oxytocin , which push out the breast or let down the milk .
1. spine and sacrum
2. atlas and axis
3. intervertebral discs
4. nucleus pulposus