With Respect to the Middle-Class Family After 1820, All of the Following

With respect to the middle-class family after 1820, all of the following explain the decline in family size in general and in the birth rate in particular EXCEPT

A) parents' desire to improve the standard of living of themselves and their children.
B) the use of birth control methods.
C) delaying marriage until one had the financial means to support a family.
D) a view of family more geared to functional usefulness than affection.