Which of the Following Statements Identifies a Correct Reason for Demographic

Which of the following statements identifies a correct reason for demographic transition?

A) The dependence on child labor is negligible in urban families compared to rural families.
B) The increase in the migration of labor from urban to rural areas reduces fertility.
C) The cost of rearing children is lower for urban families compared to rural families.
D) The transition from a rural economy to an urban economy reduces income below the subsistence level, reducing fertility and the size of families.