Answer: Observable properties
Explanation:
The troposphere has the highest density.
There are exchanges that happen continuously in our bodies. One exchange is the gas exchange, or respiratory, system. This is the system where carbon dioxide is released from the lungs into the air, and oxygen is taken into the lungs from the air. This exchange happens in the air sacs of the lungs called the alveoli.
Answer:there is nothing to choose from
Explanation:
