In the 1950s, China's forest coverage was 19%, in the 1960s, 6%, and in the 1980s, it was less than 4%. As the forest coverage decreased year by year, the vegetation was greatly destroyed, which weakened the land's impact on rainwater. Storing effect, a sudden rainstorm, rolling water and sand rolling down make flood disasters serious year by year. It can be seen that the destruction of forest resources is the cause of floods. Which of the following methods is most similar to the one above? ['Cotton is a plant fiber, loose and porous, and can hold heat. Snow is frozen by water, with 40% to 50% air gap, and is also porous and can hold heat. It can be seen that loose and porous is the reason for heat preservation.', 'Divided a group of chickens into two groups. One group was fed refined white rice. The chickens suffered from a disease. They had weak feet and could not walk. The symptoms were similar to those of human beriberi. The other group was fed with shelled rice. It is speculated that something that is not contained in polished white rice in shell rice is the cause of beriberi. Further research found that this kind of thing is vitamin B1.', "Minefield in Italy repeatedly conducted an experiment. In 4 jars, put meat and fish, and then covered or covered with gauze. Flies couldn't get in, and there was no cricket. In the other 4 jars, Put the same meat and fish, open the bottle door, the flies fly in to lay eggs, and the rotten meat and fish are quickly full of maggots. It can be seen that the spawning of flies is the reason for the rotten fish.", 'The bell is energized by energizing in a glass cover with air. As the amount of extracted air changes, the ringtone becomes smaller and smaller. If the air is completely drawn out, the ringtone will not be heard at all. It can be seen that the sound is transmitted by air.']