81. Economists believe that the government's regulation of energy use is redundant, and the market can completely adjust the contradiction between energy supply and demand. If energy is really tight, then reflected in the market, energy prices will naturally rise, and energy prices will rise. On the one hand, people will reduce their use of energy because of increased use costs, and on the other hand, energy suppliers increase their supply because of increased profits. Which of the following, if true, is a powerful way to challenge the above argument? ? ['When energy prices rise, people will use more energy-efficient products.', "People will protest the government's inaction in energy management due to the unbearable increase in the cost of living caused by rising energy prices.", 'ower energy prices will stimulate people to use more energy.', 'Inelastic demand for energy.']