The price of crude oil futures rose to US $ 147 per barrel in the first half of 2008, 4.2 times the price in the same period of 2000, with an average annual growth rate of 20%, while the average annual growth rate of the world economy was about 5%, and world oil consumption demand did not appear. Jumping, sharp growth. This shows that the rapid rise in crude oil prices is not caused by changes in the world's oil supply and demand, but is the result of crazy speculation by international speculative capital in the oil futures market. If the following are true, which one cannot question the above inference? ['From 2000 to 2008, governments of various countries generally increased their strategic oil reserves.', 'Smaller economic growth always leads to greater growth in oil demand.', 'The rate of change in oil demand and the rate of change in oil prices are not symmetrical.', 'Even for international speculative capital, investing in oil futures is risky.']