21 What is the passage mainly about?
(A) Impoverishment of workers between the 16thcentury and mid-18thcentury.
(B) The mercantilist doctrine to labor force between the 16thcentury and mid-18thcentury.
(C) Social-economic factors for economic growth of countries between the 16thcentury and mid-18thcentury.
(D) Effects of low wages on laborers’ antisocial personality between the 16thcentury and mid-18thcentury.