Q: Read the following article and answer the question. Article: Things are seldom what they seem.Skim milk masquerades as cream.Anil labor-saving household appliances often do not save labor.This is the surprising conclusion reached by a small army of historians, sociologists, and home economists who have undertaken, in recent years, to study the one form of work that has turned out to be most resistant to inquiry and analysis -?namely, housework. During the first half of the twentieth century, the average American household was transformed by the introduction of a group of machines that profoundly altered the daily lives of housewives.The forty years between 1920 and 1960 witnessed what might be called the "industrial revolution in the home".Where once there had been a wood or coal burning stove there now was a gas or electric range.The dryer replaced the clothes-line; the vacuum cleaner replaced the broom; the refrigerator replaced the icebox and the root cellar.No one had to chop wood any more. And yet American housewives in 1960, 1970, 1980 and even 1990 continued to log about the same number of hours at their work as their grandmothers and mothers had in 1910, 1920 and 1930.The earliest time studies of housewives date from the very same period in which time studies of other workers were becoming popular--the first three decades of the twentieth century.The sample sizes of these studies were usually quite small, and they did not always define housework in precisely the same way.but their results were more or less consistent; whether rural or urban, the average American housewife performed fifty to sixty hours of unpaid work in her home every week, and the only variable that significantly altered _ was the number of small children. A half-century later not much has changed.Survey research has become much more sophisticated, and sample sizes have grown considerably, but the results of the time remain consistent.The average American housewife, now armed with dozens of motors and thousands of electronic chips, still spends fifty to sixty hours a... Question: What has reduced the average amount of time American housewives spend on housework? Answer:

Choose from: i. Dozens of motors and thousands of electronic chips. ii. Sophisticated survey research. iii. Larger sample sizes. iv. Housewives' full-time employment in the labor force.
A:
iv.