Which two of the following sentences from the article include central ideas of the article?
1. Spanning three centuries of
history, from the dawn of the
Industrial Age to modern times,
three diverse thinkers developed
their own landmark theories on
commerce, labor, and the global
economy.
2. As hunter-gatherer groups
formed into more organized
societies, decisions about
distributing resources and
designating jobs became more
complicated.
3. In short, competition keeps
everyone honest, because
customers treated unfairly by
one business can always go to
another one instead.
4. As society moves about the ordinary business of life, económica always hums along in the background.

A. 1 and 2
B. 3 and 4
C. 1 and 4
D. 2 and 3