During the mid-1800s, the development of the factory system in the United States contributed to A.
a decline in the number of immigrants.
B.
the rapid growth of rural communities.
C.
the overall lowering of the standard of living.
D.
the rapid growth of cities.

During the paleolithic, hominins grouped together in small societies such as bands, and subsisted by gathering  plants  and fishing, hunting or scavenging wild  animals. the paleolithic is characterized by the use of knapped stone tools, although at the time humans also used  wood  and bone tools.