Answer:
Cells make up the smallest level of a living organism such as yourself and other living things. The cellular level of an organism is where the metabolic processes occur that keep the organism alive. That is why the cell is called the fundamental unit of life.
TOPOGRAPHY AND ELEVATION .
The best answer is D, birds.
For more information and details on the way a bird's respiratory system works:
https://asknature.org/strategy/air-flow-patterns-facilitate-efficient-gas-exchange/
I did this in my class a year ago and as far as i remember it was in the 1700 but i think 1767 to be exact
