Beyond just identifying the correct answer as D (cattle feed), it's good to know something about the economic history of the 1970s that makes that the correct answer. Beef consumption in the United States hit a peak in the 1970s at about 90 pounds per person annually. With demand for beef climbing, Wall Street investors poured money into the market and cattle production was pursued at aggressive rates. But that led to oversupply and to escalating prices for feed grain for cattle. So profits in cattle diminished quickly. Since the peak for beef demand in the 1970s, the consumption of beef per capita has fallen to less than 60 pounds, while chicken consumption has doubled during the same span of years, so that chicken is now as much in demand as beef as a food commodity.
