From 1973 to 1986, growth in the United States economy was over 33 percent, while the percent growth in United States energy consumption was zero. The number of barrels of oil being saved per day by energy efficiency improvements made since 1973 is now 13 million. If the information above is correct, which of the following conclusions can properly be drawn on the basis of it? ['A reduction in the consumption of gasoline was the reason overall energy consumption remained steady.', 'Oil imports cannot be reduced unless energy consumption does not grow at all.', 'The development of nontraditional energy sources will make it possible for the United States economy to grow even faster.', 'It is possible for an economy to grow without consuming additional energy.']