3. Which of the following alternative explanations of the change in the cash value of children would be most likely to be put forward by sociological economists as they are described in the passage？
（A） The cash value of children rose during the nineteenth century because parents began to increase their emotional investment in the upbringing of their children.
（B） The cash value of children rose during the nineteenth century because their expected earnings over the course of a lifetime increased greatly.
（C） The cash value of children rose during the nineteenth century because the spread of humanitarian ideals resulted in a wholesale reappraisal of the worth of an individual.
（D） The cash value of children rose during the nineteenth century because compulsory education laws reduced the supply， and thus raised the costs， of available child labor.
（E） The cash value of children rose during the nineteenth century because of changes in the way negligence law assessed damages in accidental death cases.
4. The primary purpose of the passage is to
（A） review the literature in a new academic sub-field
（B） present the central thesis of a recent book
（C） contrast two approaches to analyzing historical change
（D） refute a traditional explanation of a social phenomenon
（E） encourage further work on a neglected historical topic
5. It can be inferred from the passage that which of the following statements was true of American families over the course of the nineteenth century？
（A） The average size of families grew considerably.
（B） The percentage of families involved in industrial work declined dramatically.
（C） Family members became more emotionally bonded to one another.
（D） Family members spent an increasing amount of time working with each other.
（E） Family members became more economically dependent on each other.