I believe it would be the Umbilical Region
B. Old Stone Age.........................
B. People are less physically fit and productive.
Answer:
Breathing is essential for all living beings. It is basically a process where the external air is inhaled into the lungs. The lungs use up the oxygen from the air and send out carbon dioxide into the external environment. This is also called exhaling.
The exchange of air between the external and internal environment of a living being is known as breathing. The constant intake and utilization of oxygen by the body is what keeps the organs working, and the living being alive.
