(C) they used trans-Saharan trade route to acquire expensive ivory.
Answer: Drainage or absorption of amniotic fluid
Explanation: Amniotic fluid act as a cushion to a growing foetus and provides the foetus with nutrients and biochemical products from the mother via the blood vessels of the placenta. When the date of baby delivery grows closer the lungs absorbs some of the fluid. Soon after birth the newborn's first step to independence begins with breathing on its own.They gasp and cry taking in air that fills the lungs. This expels the remaining amniotic fluid that was in the lungs and begins its own independent breathing.
I think either neutral ph or more enzyme
