What was an effect of the rapid growth of mills in the north?
a. demand for southern cotton increased.
b. demand for machines and parts increased.
c. women took jobs working at machines.
d. all of the above
(apex)

All of the above

Explanation:

During the Industrial Revolution in the USA, the cotton industry was key to great social and economic changes. This increased the demand for southern cotton to feed the production lines as well as for machine parts, as machines had to be constantly improved for more efficiency. Women entered the labor force, as the plants usually employed young, single rural women and children.