European settlers forced many changes on Native Americans, but some of the greatest changes were ones they did not expect. Which of the following statements describes a change that was not intentional?

a) Native Americans were not immune to Old World diseases and millions died.
b)Spanish conquistadors enslaved Native Americans and forced them to mine or farm.
c) Native Americans began manufacturing their own guns after the European examples.
d) Some Native Americans were forced by European missionaries to convert to Christianity.