D. Were nomads who hunted and gathered
1. Where are things located
And 2. Why are they there
The appropriate choice for the non-event is ...
... A. The costs of sewing machines began to increase.
_____
Interchangeable parts generally reduce costs and increase demand (and production).
One simple and easy way that scientists can accurately date fossils found is through the ground levels. When you take a big chunk out of the earth, you can see the changes in the texture in the "ground" Each "layer" represents a set of years. And as you get further and further into the ground, fossils become older and older.
