Since the 1950s, the number of large tornadoes that have erupted each year has increased from about 10 to 15 times. At the same time, human activities have surged and the global climate has significantly warmed. Some people believe that climate warming has caused tornadoes. Increased number of times. Which of the following, if true, cannot weaken the above conclusion? ['There are various types of tornadoes. After global warming, the number of small tornadoes has not changed significantly.', 'The warm climate is a necessary condition for the formation of tornadoes, and the formation of almost all tornadoes is related to the local high temperature.', 'Despite global warming, tornadoes still occur most in the Midwestern United States, and tornadoes are rare in other regions.', 'Tornado is the product of thunderstorm weather (that is, local convection weather accompanied by lightning strikes and lightning). As long as extremely strong air convection occurs during thunderstorms, tornadoes are prone to occur.']