River valley trade made them key economic areas.
Hope this helped. :)
I would say D. Fossil fuels must be burned to release their energy.
If tectonic plates collide it forms convergent plate boundaries. if tectonic plates separate they form divergent plate boundaries
Many intervening variables that could affect the performance of a freely suspended compass and achieve a linear measurement. Some of these variables are enumerated below but not limited to these items.
1. Temperature Induced
2. Current Stabilization
3. Temperature effects on the materials
4. AC and DC
