An experiment or survey must be controlled in order to receive accurate results.
In an experimental group, the independent variable is changed. But in the control group, the independent variable stays the same.
Answer-
Dark Side- Lunar hemisphere that is not currently lit by the sun. Hope this helps!!
Answer
d.crust
Explanation
because he covered the layer of the earth
The respiratory system that allows for Gas Exchange happens between Alveolar Spaces and Capillaries