Ecological immigration refers to immigration in order to protect the special ecology of a certain area or to restore the ecology of a certain area. It also refers to immigrants who have migrated the local people as a whole due to the poor natural environment and the conditions for poverty reduction on the spot. According to the above definitions, Which of the following are ecological migrants:. ['Villagers in the mountainous area of Guizhou Province were moved to another country due to petrification.', 'Hundreds of years ago, the residents of the Central Plains moved to the south to avoid the war and became Hakkas.', 'A village is located in a valley and the transportation is very inconvenient. In order to get rich faster, the villagers collectively decided to move outside the mountain.', "Zhang San's parents live in the Three Gorges Reservoir area. Due to the repair of the reservoir, their parents sold their property and came to Shanghai to live with Zhang San."]