Why was there a need for reform in the us during the mid-1800s?
a. cities were expanding rapidly and crime was increasing
b. workers were working long hours in dangerous factories
c. slavery was spreading into new states
d. all of the above

D

Explanation:

all those things were happening at the time. as time goes on history will focus on more specifically what is going on.

food chain i would say only because there is competition on getting food and survival

four sitting presidents have been assassinated while in office but the first was abraham lincoln,