What basic principle of mercantilism was disproved by Adam Smith in his book, The Wealth of Nations? Select one:

a.
that there was a fixed and limited amount of wealth in the world

b.
that foreign goods were always inferior because British factories were better

c.
that workers would stop working if they were not provided with a minimum wage

d.
that the rich could only get richer if the poor had a way to improve their own lives