200,000 is the population density.
Answer:
A. Burning fossil fuels
C. establishing state parks
E. using renewable energy sources
Explanation:
Answer:
research question: how do different humidity levels affect the heights of different types of trees
independent variable: humidity level
dependent variable: tree height
constants: temperature, light, duration of time
control group: tree left outside in normal conditions
Explanation:
Hey there!
I believe the answer you're looking for is radio wave
Hope this helps!